To Float or not to Float...

The buzz is your answer.

Best,

E

I believe the "float" switch is there for some equipment which have circuits that depend on a "floating ground".  It is always best to disable "float" and set it to "ground" position unless there is a reason not to.

I've never had any hum or buzz problems, but I follow this:
 
Ideally the system should only have one ground point via the mains plug, be it amp, preamp or source. This way there is no "earth loop" via the grounds and your house earthing. As all earths are carried to the all three components via the interconnects to the ones that aren't.
Myself I like the one earth to be at the poweramps end because it's the least sensitive component and any rf gets dumped to it. Others like it to be the preamp because it's in the middle and represents "star earthing".

Cheers George  

georgehifi

... This way there is no "earth loop" via the grounds and your house earthing. As all earths are carried to the all three components via the interconnects to the ones that aren't ...

This is extremely dangerous - interconnects are not intended to carry safety grounds. Following this practice means that a component's chassis could be energized with lethal voltage. Safety grounds should be "earthed" only through a properly grounded power cord, or a chassis that is itself directly connected to a safety ground.

I have a DeHavilland preamp which has a switch allowing one to "float" the ground. I’ve always used it in the "float" position, however recently, perhaps due to some connectivity issues with my interconnects, there is a small buzz emanating from my speakers with the switch in this position.

Like Erik said above, which ever way sounds the best.

perhaps due to some connectivity issues with my interconnects, there is a small buzz emanating from my speakers with the switch in this position.

You might try cleaning the male and female connectors with some isopropyl alcohol.

cleeds is correct about substituting the small gauge signal ground wire of ICs in place of the safety equipment grounding conductor of the power cord.

As for the ground lift switch on your preamp.... Do you know for sure what ground it actually lifts?
Does it lift the preamp circuit/ground from the chassis? (User safe)
OR
Does it lift the safety equipment grounding conductor of the AC power cord from the chassis of the preamp? (Dangerous, not user safe. I have read where some manufactures do this.)


https://positive-feedback.com/Issue12/dehavilland.htm

Right off the back, I had to deal with a minor hum problem that occurred upon powering up the UV. This happens from time to time with a component. Normally, I have to pull out my floater plugs, isolate the problem, and float the ground on that side. Fortunately, deHavilland placed a feature on the UV that I don’t see often enough on fine preamps: a switch on the back panel to float the ground. One flip of that switch fixed the hum problem immediately.

I noticed in the picture showing the switch it is right next to the IEC power inlet connector. Does the switch lift the AC mains safety equipment ground from the chassis? IF the switch does lift the safety equipment ground from the chassis then that is the same as using a ground cheater adapter to lift the ground at the wall receptacle outlet.
You can easily find out 100% for sure with a multimeter.

Jim

Thanks for all of your responses.  Cleeds triggered the solution when he (or she) wrote "a properly grounded power cord", which reminded me that I was having intermittent problems with the connecting plug of the preamp's power cord.  Swapped out the power cord and problem solved.  I also have a pair of DeHavilland mono block amps with the same ground/float switches, and in the manual it states that leaving the switch in the "float" position may result in a "cleaner sound".  At any rate, a fully functioning grounded power cord has done the trick... 

This is extremely dangerous - interconnects are not intended to carry safety grounds.

No it’s not as many sources have two pin mains plugs and rely on the ground from the next stage via the interconnect same goes for some preamps.

If you were to have a grounded mains plug at the source and the poweramp you have created an earth loop with the ground wire between the power points as the interconnect carry the earth as well.

Cheers George

georgehifi

If you were to have a grounded mains plug at the source and the poweramp you have created an earth loop with the ground wire between the power points as the interconnect carry the earth as well.

It is clear that you are confused about this issue. The matter of ground loops is only an issue when the grounds are of different potential. Having multiple safety grounds in an audio system is not itself an inherent problem.

As for interconnects carrying safety grounds again, you are confused, particularly with respect to balanced connections.

georgehifi
2,763 posts                                                                    09-13-2017 5:08am

 This is extremely dangerous - interconnects are not intended to carry safety grounds.

No it’s not as many sources have two pin mains plugs and rely on the ground from the next stage via the interconnect same goes for some preamps.

What if all the AC powered audio equipment uses two pin mains plugs? (There in the equipment uses internal double insulated AC power wiring.)

The safety equipment ground is for electrical safety. It is not needed for the operation of the equipment electronics or SQ, (sound quality), of the equipment. In fact sometimes an equipment ground can harm the SQ of audio equipment. It can introduce noise and of course, as cleeds said in his last post, it can cause a ground loop when a difference of potential, voltage, exists between equipment grounds.

weebeesdad OP
54 posts                                                                            09-12-2017 12:48pm


Thanks for all of your responses. Cleeds triggered the solution when he (or she) wrote "a properly grounded power cord", which reminded me that I was having intermittent problems with the connecting plug of the preamp’s power cord. Swapped out the power cord and problem solved. I also have a pair of DeHavilland mono block amps with the same ground/float switches, and in the manual it states that leaving the switch in the "float" position may result in a "cleaner sound". At any rate, a fully functioning grounded power cord has done the trick...

Cleeds triggered the solution when he (or she) wrote "a properly grounded power cord", which reminded me that I was having intermittent problems with the connecting plug of the preamp’s power cord. Swapped out the power cord and problem solved.

It may have stopped the buzzing but it, just my opinion, is only a band aid that stops the buzzing. Just a guess on my part you may have a cold solder connection internally with the return signal ground output jacks on the preamp. When you close the ground lift switch the signal ground connection is being completed through the power cord equipment ground wires. There in the signal ground of the equipment is connected to the chassis of the equipment. The safety equipment ground is connected to the chassis. (If designed properly the signal ground does not connect directly to the chassis. May be through a resistor). When you close the ground lift switch on the preamp you completed the signal ground circuit from the preamp to the power amp through the power cords equipment ground wires. Preamp power cord >> to the wall receptacle "U" shape equipment ground contact >> to the power cord of the power amp.

Jim

Cleeds wrote:

This is extremely dangerous - interconnects are not intended to carry safety grounds. Following this practice means that a component's chassis could be energized with lethal voltage. Safety grounds should be "earthed" only through a properly grounded power cord, or a chassis that is itself directly connected to a safety ground.

This is absolutely correct, and it amazes me that audiophiles will accept a potentially lethal component in their house.  Interconnects are not designed to carry a safety ground.

There are several techniques for eliminating ground loops while at the same time having every component's SIGNAL ground connected to the SAFETY ground (i.e. the chassis and ground lug of the mains outlet) .

Look at section 15.10 of the document downloadable on this page for one sample solution:  http://www.valvewizard.co.uk/Grounding.html

It would be easy to retrofit the above suggested circuit (4 parts) into a vacuum tube component (especially one that's hard-wired).

Cheers,
Thom @ Galibier Design

What if all the AC powered audio equipment uses two pin mains plugs?

Then this is lethal, there must be always a ground.
Look at most CD players, tuners, phono stages ect, they mostly have a figure 8 mains plug on the back yes just two pin, and yes it get's it's earth ref from the next stage, the pre if it's earthed, via "guess what" the interconnects.

Cheers George  

georgehifi

Look at most CD players, tuners, phono stages ect, they mostly have a figure 8 mains plug on the back yes just two pin, and yes it get’s it’s earth ref from the next stage ...

I thought we were talking about components manufactured in this millennium, which typically use IEC connectors and either have safety grounds or special construction to insulate the chassis. It’s rare for modern equipment to use figure-eight, two-prong AC connectors.

You might still be relying on obsolete knob-and-tube wiring in your house, too. But most of the world has moved on from that.

No matter how you to try to twist this discussion, @georgehifi , interconnects are not intended to carry a safety ground. And there is no inherent risk in having a system with multiple safety grounds. The goal is to have equal electrical potential of each ground - rather than to bypass safety grounds.

georgehifi
2,764 posts                                                                       09-13-2017 11:20pm

What if all the AC powered audio equipment uses two pin mains plugs?

Then this is lethal, there must be always a ground.
Look at most CD players, tuners, phono stages ect, they mostly have a figure 8 mains plug on the back yes just two pin, and yes it get’s it’s earth ref from the next stage, the pre if it’s earthed, via "guess what" the interconnects.

Cheers George

No, an earth ground is not needed when the equipment is Class ll (Double Insulated) power rated.

If a piece of audio equipment is Class ll rated the power cord will be two wire. In the US and Canada at least the NEMA 5-15P or 5-20P plug will be polarized so it can only plug into the wall receptacle in one direction.

For detachable power cords there are of number of IEC connectors available.
The C17/C18 15 amp combo is widely used.
https://en.wikipedia.org/wiki/IEC_60320

Picture of power cord with a C17 female IEC connector.
http://www.yunhuanelectric.com/Clkj_Images/upfile/image/IEC-60320-C17-Power-Connector.jpg

Picture of the IEC C18 inlet connector.
http://usr.audioasylum.com/images/1/14409/C18_IEC_Inlet.jpg

Where the inlet IEC is a C18 a 3 wire power cord with a female C13 connector can be used. (Though NO earth connection is made to the equipment.)
https://www.kenable.co.uk/images/RB-291_i1.jpg

Here is a picture of the back of a Marantz PM8005 Integrated amp. Note the inlet connector is non earth grounding.
http://www.us.marantz.com/us/Products/Pages/ZoomImage.aspx?img=/Assets/images/products/PM8005/XL_pm8...

Here is a picture of the back of a Marantz SA8005 player.
http://www.us.marantz.com/us/Products/Pages/ZoomImage.aspx?img=/Assets/images/products/SA8005/XL_sa8...
Note the inlet connector is a 2 wire non grounding type.

NO earth ground connection is used.

~ ~ ~ ~ ~

As for using the small gauge signal ground wire of an IC for a safety equipment grounding conductor.

First the IC cable is not approved to be used as an equipment grounding conductor by any recognized third party testing laboratory. NONE.

IF a ground fault event, from the hot conductor to chassis on the load side of a small amperage value fuse were to occur it is possible the small gauge signal ground wire might carry the current long enough to cause the fuse to blow. Might.

If the ground fault event happened on the line side of the fuse, NO WAY. In the USA the typical 15 amp branch circuit breaker could pass 100 amps before it would react to the ground fault event and trip open. NO way the small signal ground wire of the IC can handle that kind of current. What will happen the small wire will blow, burn, itself free at one end or both where it connects to the connector. If the IC jack on the back of the audio equipment is soldered directly to a circuit board it may melt the solder and the arcing that follows may cause damage to the small circuit trace.

Now what if a ground cheater is used on a big honken Krell power amp that uses a 15 amp magnetic breaker to protect the amp. Do you think the small signal ground wire in the ICs will carry the high ground fault current and cause it to trip open?

Jim

Correction:

If a piece of audio equipment is Class ll rated the power cord will be two wire. In the US and Canada at least the NEMA 5-15P or 5-20P plug will be polarized so it can only plug into the wall receptacle in one direction.

That should read NEMA 1-15P plug. A 125V 15 amp two wire polarized plug.
Example:http://rockyroadweb.company/ebay/2_prong_stereo_cord1.jpg

They make a NEMA 1-20P plug, but I have never seen one.....

Jim

First the IC cable is not approved to be used as an equipment grounding conductor by any recognized third party testing laboratory. NONE.

This is exactly how more than half the source equipment that use earth figure eight two pin mains cable get their earth reference, via the interconnect.
We in Australia have one of the most stringent mains safety rules and regulations as we are 240v (lethal), nearly our sources have their mains reference given by the interconnect, and guess what we don't have many earth hum noise problems, because we don't get many ground loop issues.
We may get a earth loop problem when two mono blocks poweramps amps each have earths and are plugged into different power points who's earths take different routes around the house, this can sometimes create a loop, usually then one is floated (not ideal I admit) or we get longer leads and plug then both into the same power point.  

Cheers George   

This is exactly how more than half the source equipment that use earth figure eight two pin mains cable get their earth reference, via the interconnect.

IF the equipment is Class ll (Double Insulated) Listed that uses a two wire power cord and plug, why do you think it still needs to be earth grounded?

Jim

You clearly don’t know or understand.
It still has to get a total system reference earth via the interconnect shield, if you disconnected that shield at either end (and be left with a single wire connection) you get a massive noise.

Cheers George

georgehifi
2,766 posts                                                                   09-14-2017 7:50pm

You clearly don’t know or understand.
It still has to get a total system reference earth via the interconnect shield, if you disconnected that shield at either end (and be left with a single wire connection) you get a massive noise.

Cheers George

George,

The safety equipment grounding conductor is for electrical safety. It is not needed for the normal operation of home audio equipment. IF the audio equipment is not Class ll power rated, and Listed, for use of a two wire cord and plug then a three wire cord and plug shall be used and the equipment grounding conductor shall be bonded, connected, directly to the metal chassis of the equipment... The equipment grounding conductor is there to carry any leakage and or ground fault current back the electrical service service entrance neutral conductor where all branch circuit equipment grounding conductors connect. (Note the electrical service entrance neutral conductor is bonded to the service equipment cabinet enclosure as well is connected to the earth.)

2014 NEC

Grounding Conductor, Equipment (EGC). The conductive path(s) that provide a ground-fault current path and connects normally non-current-carrying metal parts of equipment together and to the system grounded conductor or to the grounding electrode conductor, or both.

~ ~ ~

Georgehifi
It still has to get a total system reference earth via the interconnect shield,

No it does not need an earth reference.

I don’t think you understand the difference between an equipment grounding conductor and a signal ground conductor.

Yes the signal ground wire of an interconnect cable must be connected to the signal ground of the source and the signal ground of the receiving load.

As for a shield. Not all ICs are shielded. And when a shielded IC has a separate signal ground wire, the shield as a rule is connected at one end only. Granted the shield of a coax cable must be connected at both ends. It is the return signal ground conductor.


Full circle.....

georgehifi
2,766 posts                                                              09-13-2017 5:08am

This is extremely dangerous - interconnects are not intended to carry safety grounds.

No it’s not as many sources have two pin mains plugs and rely on the ground from the next stage via the interconnect same goes for some preamps.

If you were to have a grounded mains plug at the source and the poweramp you have created an earth loop with the ground wire between the power points as the interconnect carry the earth as well.

Cheers George

Jim
.

No it's you that doesn't understand, as interconnect shields are kept at earth potential, some thorough a very low ohm resistor, if they weren't they'd be useless as a shield for rf.

Cheers George   

Also look at the fact that you can buy mains earth cheater adaptor plugs, which give you the option to float the earth of that piece of equipment they are attached to from most hi-end audio stores, for doing exactly what I said before, to have one only earth point in the system as not to create a loop with the mains they are plugged into. Also many pro equipment have earth float switches on them, as do some hi-end audio, even the John Curl designed  Halo JC-1 monoblocks have this also to stop loop problems if they are in different power points.
http://www.parasound.com/product-images/jc1_rear.jpg

Cheers George

georgehifi
2,768 posts                                                                 09-14-2017 10:08pm


No it’s you that doesn’t understand, as interconnect shields are kept at earth potential, some thorough a very low ohm resistor, if they weren’t they’d be useless as a shield for rf.

Cheers George

George,

If what you say is true how possibly does the two pieces of Marantz audio equipment (see Links below) work as designed. Neither piece of equipment uses an earth equipment ground connection. In the world of the two pieces of audio equipment the only ground that exists is the B- power supply that connects to the metal chassis of the two pieces of equipment. I am pretty sure the signal ground of each piece of equipment is also connected to B- and chassis. The metal enclosure rejects RFI just fine without being connected to an earthed ground. How can that be?

I could use an isolation transformer and float the secondary winding above ground and feed the Marantz SA/CD player and Marantz integrated amp and they would operate and sound as designed. They wouldn’t even know an earth ground exists outside their boxes.

Here is a picture of the back of a Marantz PM8005 Integrated amp. Note the inlet connector is a 2 wire non grounding type.
http://www.us.marantz.com/us/Products/Pages/ZoomImage.aspx?img=/Assets/images/products/PM8005/XL_pm8...

Here is a picture of the back of a Marantz SA8005 player. Note the inlet connector is a 2 wire non grounding type.
http://www.us.marantz.com/us/Products/Pages/ZoomImage.aspx?img=/Assets/images/products/SA8005/XL_sa8...


NO earth ground connection is used. How do they possibly play together with one another? The job of the ICs is to transfer the signal from the SA/CD player to the integrated amp. That is their purpose.

Jim

I’ve tried.

No use discussing it any longer, as your set in your ways. 

Cheers George

georgehifi
2,768 posts                                                                    09-14-2017 10:39pm


Also look at the fact that you can buy mains earth cheater adaptor plugs, which give you the option to float the earth of that piece of equipment they are attached to from most hi-end audio stores, for doing exactly what I said before, to have one only earth point in the system as not to create a loop with the mains they are plugged into. Also many pro equipment have earth float switches on them, as do some hi-end audio, even the John Curl designed Halo JC-1 monoblocks have this also to stop loop problems if they are in different power points.
http://www.parasound.com/product-images/jc1_rear.jpg

It may be called a ground cheater but that is/was not its’ intended design an Listed use.
The reason for the 3 wire to 2 wire adapter is to connect an appliance or piece of equipment to a grounded 120Vac power system where the 2 wire branch circuit, hot and neutral conductors, were installed in a metallic raceway, conduit, and metal box. The pigtail or ground strap tab on the adapter was to be connected to the center 6/32 trim screw, that supports the cover plate to the 2 wire duplex receptacle. (Note the female 6/32 threaded hub is mechanically, electrically, connected to the supporting back strap of the 2 wire duplex receptacle.) Ground conductivity/continuity from the duplex receptacle metal back strap to the metal box was as good as could be expected back in those days.

So bottom line they were not designed to lift the ground. Though in many cases that is what they ended up being used for.

georgehifi said:
"Also many pro equipment have earth float switches on them, as do some hi-end audio, even the John Curl designed Halo JC-1 monoblocks have this also to stop loop problems if they are in different power points."
http://www.parasound.com/product-images/jc1_rear.jpg

I would bet John Curl does not lift the safety equipment ground from the chassis of any piece of audio equipment he designs. I would bet the ground lift switch seen on the back of the amp lifts the signal ground from the chassis.

Jim

Whatever, you have your view, that has no other.

Cheers George

John Curl does not lift the AC mains safety equipment ground from the chassis on the JC 1 amp.

"TECHNICALLY SPEAKING",     page 14

3. Use the Ground switch on the JC 1 to eliminate most ground loops. This separates the JC 1’s signal input ground from its chassis ground to isolate unwanted voltage in the ground shield of the unbalanced (RCA) input cable. Be sure your system installation is finished before you try moving the Ground Lift switch from its “Normal” to its “Lift” position.

https://parasound.com/pdfs/JC1Manual.pdf

.

"Be sure your system installation is finished before you try moving the Ground Lift switch from its “Normal” to its “Lift” position."

This statement proves my point, that then the amp circuit will get it’s system ground reference from the next stage via the interconnects shield, and if the shield were disconnected it could have large amount of noise and maybe even damage the amp.

Cheers George

The most quiet amps I've used "float" the ground.  

weebeesdad OP
54 posts                                                                            09-12-2017 12:48pm

Thanks for all of your responses. Cleeds triggered the solution when he (or she) wrote "a properly grounded power cord", which reminded me that I was having intermittent problems with the connecting plug of the preamp’s power cord. Swapped out the power cord and problem solved. I also have a pair of DeHavilland mono block amps with the same ground/float switches, and in the manual it states that leaving the switch in the "float" position may result in a "cleaner sound". At any rate, a fully functioning grounded power cord has done the trick...

@weebeesdad,

I checked and was told the ground lift switch lifts the signal circuit from the chassis/AC mains safety equipment ground.
The AC mains safety equipment ground is always connected to the chassis of deHavilland audio equipment for electrical safety.
It is recommended the user "float" both deHavilland mono blocks and close the ground lift switch on the preamp.

The chassis of the power amps will still be grounded, connected, to the AC mains power outlet safety equipment ground.

Jim

Thanks, Jim.  I also use the preamp with a solid state amp that has no ground lifting switch, and keep the preamp switch in the "float" position.  Any danger in that?? 

@weebeesdad ,

No danger at all. The switch only lifts the audio circuit from the chassis ground.
(The AC mains safety equipment ground)

The AC mains safety equipment ground remains connected to the chassis at all times. In the event of a Hot to chassis ground fault event the safety equipment ground wire in the power cord connected to the preamp will carry the fault current to the wall receptacle equipment ground contact.

Are you using the preamp with the SS amp at the present time with the switch on the preamp in the float position?

I also use the preamp with a solid state amp that has no ground lifting switch, and keep the preamp switch in the "float" position.

Jim

Jim -
I have always used the preamp in the "float" position, whether it was with a solid state or tube (including the DeHavilland mono blocks) amp.  My impression was that sonically this was the preferred position, and as I mentioned the manual for the mono blocks even states a potential sonic improvement keeping the switches in the "float" position as long as there are no accompanying noises or buzzes (I can't seem to find the preamp manual to check, however it was planted in my head from somewhere (probably the manual) to keep that switch at "float").  Only recently did the buzzing begin which corresponded with some connectivity problems related to the preamp's power cord.  Now that I have switched to a different power cord, there is no more buzzing or noise, and all grounding switches are set at "float". 

weebeesdad said: 09-16-2017 7:54pm

Now that I have switched to a different power cord, there is no more buzzing or noise, and all grounding switches are set at "float".

I would say that rules out an interconnect/s causing the buzzing problem.
Audio system sounds fine now, no buzzing, same interconnects.

Through experimenting, listening, you found the power cord you were using on the preamp was causing the buzzing sound you were hearing.

Exactly why is still the unknown, imo.

What puzzled me you said, in an earlier post, when you closed the ground lift switch the buzzing would stop. If the integrity of the continuity of the equipment ground wire connection, of the power cord, was compromised somewhere from the male plug >>> through the IEC connector, >>> through the ground contact of the preamp IEC inlet connector, closing the ground lift switch would not make any difference. But you found closing the float ground switch did.....

What exactly could be the cause of the buzz? At one point I considered poor contact pressure between the hot and or neutral current carrying conductors between the IEC female connector, on the end of the power cord, and the male inlet connector on the back of the preamp. Even a slight arcing would induce RF noise into the preamp, imo. Sounds plausible to me.....

But why closing the ground lift switch would stop the buzzing sound?
When closed it connects the preamp’s audio circuitry, signal ground circuit, back to the chassis of the preamp.

This is where John Curl would say, this is where the test equipment is brought on board to measure and found out the why.

Something to throw into mix of thought for the why. Here is a response from Charles Hansen to a post of mine.

Close

Posted by Charles Hansen (M) on August 26, 2008 at 21:40:33

In Reply to: RE: If you’re referring to the ’double insulated’ designation that allows manufacturers of small posted by jea48 on August 25, 2008 at 11:36:39:

< < The AC power wiring is double insulated. The case is floating.... > >

Actually the case is connected to the signal ground of the internal circuitry.

I think the main reason that most manufacturers use 3 wire power cords with a safety ground is ignorance. It’s the easiest way to ensure safety, and it’s also the method most commonly espoused in textbooks.

Kind of like FETs versus bipolar transistors. All the textbooks focus on bipolars. Not much is generally known about FETs. So designers follow the path of least resistance. It’s too much work to dig up all the stuff to learn about some other technology like FETs or double insulation.

And then his response to another post of mine.

RE: Thanks Charles for your response, but you left us, me, hanging.

Posted by Charles Hansen (M) on August 27, 2008 at 22:50:26

In Reply to: Thanks Charles for your response, but you left us, me, hanging. posted by jea48 on August 27, 2008 at 16:58:04:

The only way that the case can provide any shielding for the audio circuitry is if it is connected to the signal ground. In addition, if it is left unconnected from the signal ground, then it will create unwanted capacitive feedback loops (both positive and negative) between various parts of the circuitry. Refer to Morrison’s books for additional details.

https://db.audioasylum.com/mhtml/m.html?forum=general&n=525553&highlight=double+insulated+po...

Now keep in mind the responses from Mr. Hansen are in response to my posts for audio equipment that have double insulated AC power wiring where the power cord is 2 wire with a 2 prong plug. AC mains equipment ground is not used.

So how does the above relate to your situation? Not really sure.
But what if the AC mains equipment ground is broken, open, somewhere in the bad power cord. No continuity, or sometimes intermittent continuity. With the ground lift set to float wouldn’t the chassis be acting exactly as Mr. Hansen said in his post?

All just conjuncture on my part.....

Al, (almarg),

If you are reading this post of mine what are your thoughts on the "why the buzz"

~ ~ ~ ~ ~
@weebeesdad,

Question.
What are you using for front end sources connected to the preamp? Do they use the AC mains safety equipment ground? There in, a 3 wire grounding type power cord and plug where the equipment grounding conductor, wire, in the power cord is connected to the chassis of the front end source/s ?

Jim

Jim - My only front end source is a Resolution Audio Opus 21 cd player which uses a three prong power cord which presumably grounds it.  The cd player and preamp are both plugged into a power strip which I was told is recommended for use with Naim equipment and also utilizes a three prong cord and receptacles.  I initially thought the buzzing was caused by the interconnects between the pre and power amp, however swapping them out for different interconnects did not alleviate the problem.  I was have issues with the IEC female connector on the power cord making consistent contact, and, as I reported, changing that has seemingly solved the problem.  As to why the buzzing stopped when I switched to "ground" position, the technical answer is above my pay grade and I will let those of you with greater expertise ponder that...

I have so many things plugged into my system I'm amazed at how utterly quiet it is. There are bespoke DC buzz killing power supplies on the DAC and phono preamp, a PS Audio Humbuster III for the tube and SS amps, no ground pin was provided for the main preamp (Kavent S-33 dual mono masterpiece) weirdly, but doesn't seem to matter, and I did have to lift the ground via a small switch on a REL Q150e due to a small hum issue. Otherwise, although my SEP main power amp is working fairly hard in its Class A massive 12 watts (or something) per side, it is also dead quiet…blacker blacks, redder reds, more opaque opaqueness, you know what I mean.

Never lift grounds on power amplifiers. you don't want that to go live with the currents that can easily kill you. If however your house is correctly earthed the breaker should go before there is any damage done to the equipment or more importantly you. Unless as said above manufacturer has a ground lift capacity on the board " no "always leave grund in place. if you have a ground loop "buzzing" noise lift the earth on the pre amp as interconnects can more than likely handle that current going back to earth. But as said check connections are tight and that balanced connectors are wired the right way in phase etc. Pull the power amplifier as far away from the sensitive circuits in the preamplifier as some are oversensitive and away from central heating circuits , strip lighting. There are many noise sources that cause these issues. Often here is no need to jump to lifting mains earth on audio gear.

jea48 is the go to person when it comes to electrical wiring and safety.  Trust his advice. 

 I also have a pair of DeHavilland mono block amps with the same ground/float switches, and in the manual it states that leaving the switch in the "float" position may result in a "cleaner sound".  At any rate, a fully functioning grounded power cord has done the trick...

If the grounding scheme of the audio equipment is properly designed and executed there will be no need for a ground lift switch. The chassis will simply be properly grounded through the AC power cord's third prong and doing so will in no way affect the sound.

@jea48 has been correct in his assertions.

linndec

... if you have a ground loop "buzzing" noise lift the earth on the pre amp as interconnects can more than likely handle that current going back to earth.

This is bad advice and potentially unsafe. Interconnects aren’t designed to handle this current, and lifting the AC ground could energize component chassis with lethal voltages.

It amazes me how often people here misunderstand ground loop problems. The issue isn’t having multiple paths to ground; the problem is having multiple ground paths at varying potentials.

This is one of the benefits of using dedicated AC lines - it simply makes it easier to have clean grounds. I have a biamplified system with lord knows about many ground paths! I don’t have any hum issues, though, because of these clean, direct grounds ... all at the same voltage potential.

If your equipment has a ground-lift switch then it should be safe to use if you desire. Whether the connected components have the earth ground prong or not doesn't matter as long as they're properly designed. Simple as that. 

Unless you plan on opening your gear while it's connected to power (or immediately after a disconnect) then you have nothing to worry about. 

 A strong surge can destroy your gear regardless, so get redundant surge protection on your lines. 

I corresponded with Kara Chaffee, the designer of my preamp and mono blocks, and she concurred with Jim's post of 9/16/2017. The "float" switch only lifts the audio circuit from the cassis ground and the AC mains equipment ground remains connected to the chassis through the 3 wire grounding type power cord. Kara feels the units sound best with the audio circuits floated and that's the way I've always run them with no noise or buzz (except for aforementioned power cord malfunction).