Power Amplifier Longevity

If you do get an older amp be sure you can find service manuals and schematics for it. Most everything is repairable with some exceptions. But it is much harder without a schematic.

I have a pair of monoblock 125 w. Class A/B tube amps with humungous power (electrolytic) storage caps.  They are several decades old and are fully exposed to the air.  The adjacent transformers run so cool that I can nearly wrap my hand around them after hours of use.  

Contrariwise, I have an EAR 890 that after 20 minutes, is nearly boiling hot and touching the transformers can melt one's skin off.  It's a Class A amp with small tubes sealed in the circuit board upside down.   This amp may need new caps in the future.

My prior Audio Research SP14 had a burned out resistor on the center of the circuit board after only 5 years of heavy use.

My McIntosh MC30s still run fine with original caps.  It runs hot as does my modified Dynaco ST70 (new larger storage caps).  

Two Yamaha CR620 receivers began to hum and caps were replaced after 35 years of use for video.

So, some caps last many decades and some probably will do to their high quality and low heat exposure.   Other caps and resistors can burn out rather quickly due to internal circuit board heat.

To one, Mr. "JHertzlee", First off. I am not trying to be mean. Nor condescending. And I am simply stating the truth as I see it when I tell you that currently? You are of a mind to be more, "Part of the problem". Than, "Part of the solution". And I truly hope that in a few years you have occasion come back. Reread what you have stated above. And, "Find the light".
 Please, It sounds like your understanding of "transduction", is from a "Tech manual". And it's "Glossary", was very limited in it's scope of understanding. You may want to do a bit of research on that one.
 Also the "Heat" comment? please rethink that. "They are called (Operating temperatures). for good reasons". OR "Should I"? Keep my Hi-End, HiFi, Very expensive components "Inside" of the freezer walk-in. Which I had modified to hold these audio components and still allow the remotes to work for function? Complete with a "Remote Control Repeater". Which means they can just stay at the brisk -22F. in the filtered, Ion rich, cold air, freezer.
Would it not sound better? And last much longer?

"Otherwise, I'm leaving that one alone".  since many would think me cruel if I was to do anything else.

 And, a percentage of your income is attained by, " doing what exactly"? 
Is there perchance a "list", of the parts type. Which would, "Automatically", get changed/replaced by any of the techs working there? "This assumes whomever dropped the amplifier off. Also agreed to pay for a full servicing of the fourteen year-old, Solid State, class A/B, two channel amp with the "Very reputable name", and without, "nary" a scratch on it!. An amp which would bring say, $3800 firm, as it sits on "Audiogon". Very quickly. 
 I would be very interested in your answer, JHertz
   Change All the main, large caps? All the little one's too on the PCB? Interior fusing? Indicator Lamps? A can of WD-40, Then a can of air to blow out the Pots and dust off the PCB? Anything else? Set the Bias if applicable, Give it a listen and then "Unless another problem rears it's ugly head"? Onto the shelf to wait for it's owner? Avg. overall cost?
 I guess "Refurbished" is now the same as "Rebuilt"? or even, "Fully Serviced"?
 And just to ask, To re-flow the avg PCB in the avg. SS amp. How much would it be? if about avg?

And the blind man yelled, "The caps are drying out. The caps are drying out."
Ha ha, Finally a "decent", conversation on the subject.

But again, many seem happy simply to put two cents in.
 And some are worth more!
Heaudio? .....So you've designed electrical equipment and brought it to market?
 It was "UL" approved and then of course, "UL-rated? But alas,"You", did not think to have any IR limiting of any type. Added for any correction or means of protection? Well, since that really doesn't mean anything. Like your words stating that I am wrong about this. Which don't mean much either....since....

 Actually?, The odds are quite high that you "Did", in fact design IR limiting into whatever you are fooling with and bringing to market. "Knowingly OR not! If the electrical device or system followed the NEC, and any other appropriate, local authorities and their addendum, "If any". And you worked utilizing the approved guidelines, materials. Tables and math, governing electrical devices, with the same intent. And the installation and "use of". In the, "Plan, build, use. Glossary and Index." sections were also utilized with an good understanding of the NEC's, "Intent".  All in accordance with the currently, "Adopted", version of the NEC?
Then you did.  Because "We" did. Otherwise it's a bit hard to get anything "UL rated"...….
 Like the guy whom invented sand? I don't believe he designed in all of "sands" insulating properties necessarily on purpose . But since he followed basic "Physics", in the design phase of said, "sand"? 
Sand now, "has", insulative properties.....
 Just sayin....

Heaudio? 
 Also, a bus fuse, "As in ANY bus fuse". Is not IR limiting?
 I guess they are just wasting our time with the fact that they ALL have an precise "IR value", at which point they fail. (Always listed in the device, "properties"), huh?  
Which is why I have used them in designs as "Temp. emergency, "IR" breaks" in switchgear systems during emergencies.
 Also, the reason for many electrical components in a system being de-rated during design is usually for use as a "Safety Factor". Typically calculated as a proportion. These tended to be, "Pre-60's-80's". Always a minimum of 1:4- 1:5. Dependent on the quality of the product line, name and reputation etc. "These days, if used at all"? " I'll notice a percentage in de-rating specs.…."
Many really do not even know or realize. That any such animal ever existed. "The safety factor as it once was". "Kinda like the declared IR value of a fuse. And it's significance in relation to a specific electrical device or system in part OR it's entirety. 

Brian
I have both an Anthem MRX 710 and an Emotiva XPA 5 for sale.  I simply don't do surround media anymore.  If interested let me know.  Both with very low miles and in excellent condition.

I have a McIntosh MC207... there 7ch amp that has been in use since 2004....16 years old. It was a dedicated theater amp that for around 7 years did not get used but a few times a year. For the last 2 years it is now in the den system and is used everyday. It still looks and works like new. 

I have a fondness for Class A amps and so paid a fair bit when one of them went south on me, but the particular model I have is quite rare so I didn't even think about not having it serviced. It was over 30 years old. I have two other amps of the same model still going strong, as well as an early Jeff Rowland amp (also 1980s) that still serves in my AV system.

On the current inrush issue, I have an early Belles class A amp that welded the contacts on the switch together due to that. After replacing the switch for the third time, I left it welded together and turn it on and off using a heavy duty power bar!

@jollygreenaudiophile2Talk about misinformation, you are full of it. Since when in the electronics world is heat a friend of ANY electronics?? Since NEVER. What are you talking about "transducers" in an amp for? Are you converting liquid flow into a 4-20 ma signal or pressure into a 4-20? maybe you are using your "transducers" to convert temperature into a 4-20 or a 1-5V signal. Give us a break. I refurb. vintage amps as a second income, caps don't just fail cus they "burst". most old caps are fine in a vintage amp, but a lot are way out of spec, some are even open with zero capactiance. This is why its standard to do the entire amp with new electrolytic caps to avoid any trouble later. 
To the guy who thinks using an amp is too hard on the caps, um... the opposite is true, show me an old amp that's been sitting in the closet for 20 years & how those caps are holding up. Old caps need to have voltage applied now & then, like reforming. Standard procedure where I work is to reform the large caps in a VFD every 3 years if they aren't being used or sold. I also use caps that are at least 10v higher in rating, using the 105 deg. for those in power section or near heat sinks.
Yea so I'm one of those guys who repalces a lot of electrolytic caps, but I work mostly on stuff that is from the 70s & early 80s, the good stuff. Both my Mcintosh power amps, one a MC2100 is still a daily driver since high school, are still running strong, so are all 4 of my Kenwood L-O7M's
So go buy some new equipment, if that is what you are into, spend 10K or more on a 7.1 channel for your TV, but its just a TV, not a hi fidelity 2 channel stereo.

I have a pair of Mac 1.2 KW amps any idea how long these will last

My 7 pieces of 30-40 year old Bryston and Audire amps and preamps are doing great.  So are my 40 plus year old turntables and tuners. I did get Bryston to rehab the preamp.  It had a badly frayed power cord, and a very slight hum when turning up the volume enough to use a low output  M/C cartridge (because a house guest left my battery powered Audire head amp on and put new batteries in it backwards. It has finally been replaced with another one I ran into.   The only other issues I have had during this time were caused by me and my friend Johnny Walker.  Another amp and preamp are dead because of my ineptitude, not from material or design flaws..

I can only speak for myself. I built a Hafler 500 in 1975-76--can't remember that far back!--and use it today.

It was in the shop recently as I was able to score an Audio Research preamp, finally!, and wanted to be sure the Hafler was OK.  

Tech said that the bias was WAY OFF for some reason, but once he adjusted it, everything measured within spec, and it sounds just fine (for a non-tube amp), old "caps" and all.

I do know that in my Sunn guitar amp they replaced the caps and possibly a few other parts, but these amps are used for playing instruments and taken on the road, so not surprised that some parts eventually fail or no longer perform in spec.

I am looking for an Audio Research tube amp to go with my preamp, and when I find one, it being tube and running much warmer than most solid state amps, I will have it checked out (can't afford a new one) for performance before putting it into the system.  Also need an EC2 or EC3 so I can keep the Hafler on the bottom end of my Maggies, so will have to have it checked as well.  

Old stuff is old; have it checked out before incorporating into your system and you should be fine.

Will something fail eventually?  Of course.  Back in the day, we got in a number of DOA items, so new is no guarantee either.

Cheers!

Quoted from United Chemicon:

(a) Operating Voltage

When in service at voltages equal to or below the rated value, the life of electrolytic capacitors is affected less by applied voltage than by operating temperature. Figures 7, 8 and 9 show life test results with various reduced voltages applied. The curves show that the life of the capacitor has not been significantly increased by a reduction in voltage. This is due to the use of proper forming voltages to minimize gas generation and leakage current. From this we can say that when capacitors are used at or below their rated voltage, the acceleration factor AV is equal to 1.

My point in choosing a capacitor to have a max voltage higher than normal is so that it handles the voltage spikes that are likely to happen.  If the AC mains was perfect, it would not be a problem.  But if any AC machinery or any kind of inductive load is running near the outlet to which your device is connected, if the devices do not have excellent filters, they will cause spikes on the AC line when powered off.  So, a cap with a higher voltage rating will favor better than one which does not.

I am not trying to increase the life of the capacitor by choosing a higher rating.  I am making it more resilient to possible spikes over the long term.  That is the essence of my argument.

@cakyol  , @heaudio123 is correct about the can size of capacitors.


It is also prudent to follow military derating curves when selecting a filter capacitor for a power supply. This puts the voltage at which the power supply is operating to be about 70-80% of the voltage rating of the capacitor. This insures the longest life of the part. Its also worth noting that the capacitor will run longer if it is charged up fairly frequently; putting the device in storage for extended periods isn't good for electrolytic capacitors. 

For your Vienna speakers and almost whatever else you might want to replace them with for moderate size room, there is Gryphon Diablo 120 integrated for sale here. Get it and forget about the age of an amp. Gryphons are built for 40 years of reliable operation under normal conditions. Sure, some break from time to time. Everything breaks from time to time. You don't need separates. Gryphon is higher level than Pass.

I have 40+ years old amps from Yamaha, Victor, Sony, in original condition that still rock. That said, it is risky business to use them in this condition without restoration service.

heaudio, I am sorry but you are not making any sense in your capacitance stuff.  Noone is APPLYING the higher voltage.  The voltage is FIXED at the rails.  The ONLY time it moves UP is when there is a surge.  The overvoltage RATING of the capacitor simply is able to absorb the extra max voltage which spikes so it does not blow the cap.  That is why I prefer the voltage rating to be high so that it indeed CAN absorb spikes.

There will be NO change whatsoever in the capacitance of a cap becoz of its voltage rating or by changing the applied voltage to it (unless temperature becomes an issue).

And the thermistors are NTC btw: 
https://www.newark.com/amphenol-advanced-sensors/cl-60/ntc-inrush-current-limiter-10/dp/81F3390

They have to be since they must settle to a LOW value with HIGHER temps otherwise you would never be able get more than quarter of the power of the amp since the current would be limited ALL the time.
A better (but more expensive) way of doing this would be using relays with a timer of course.

Hey atmasphere, good to hear your equipment has them.  Almost all transformers rated above about 300 VAs should have them but most do not.  Expensive gear is obviously better designed and it does.
Thanks

As for inrush current limiters, MOST devices sold today do **NOT** have such current limiters.

All of our equipment has had current inrush limiters installed, going back 45 years. We did this to protect the AC power switches and over the years its worked out pretty well.

Show me one piece of information in the following that indicates reduction of capacitance with its voltage rating:

https://content.kemet.com/datasheets/KEM_A4075_ALS70_71.pdf

Remember I am talking max voltage RATING not the voltage APPLIED.

Doubling the voltage will NOT halve the capacitance.  Where did you get that from ?

Show me ONE graph that shows this.

Theta the only good maker of AV equipment? Really? Trinnov? Hello?

@jollygreenaudiophile...

I guess you did not read the last part of my comment mentioning Pass Labs amps. Please read it again :-)

As for inrush current limiters, MOST devices sold today do **NOT** have such current limiters. Also, I am not quite sure how you got "fuses" lumped into the same category as a current limiting device but there is absolutely no correlation between them.

Any device which uses transformers (especially toroidals over a few hundred VAs), and electrolytic capacitors (such as the large filters on most power amps) present an almost SHORT CIRCUIT to the mains within the first cycle of the AC voltage, which lasts about 1/120th of a second. This is a very long time in the electronics world. Until the magnetic field is established on the transformer, the ONLY limit is the simple PURE wire resistance of the transformer. This can be in the very low ohms for large transformers (1 or 2 ohms max). We are talking in excess of 80 - 100 amps of inrush for 1/60th of a second. That is why lights dim for a second when some amps are switched on. In addition, on the transformer secondary side, the filter caps are a also virtual SHORT CIRCUIT as soon as power is applied. This means your rectifier is presented with a short circuit as soon as power is switched on. Again we are talking 100s of amps instantaneously until the caps start charging. Those currents, despite being on only about tenths of a second present a tremendous overload to the components, especially the rectifier and the capacitor itself.

Check out the circuit here from Nelson himself:
https://www.diyaudio.com/forums/diyaudio-com-articles/154777-burning-amplifier-ba-1-a.html

The items marked as THx (resistors with arrows thru them) are called Thermistors or NTCs (Negative temperature coefficient) meaning their resistance DROPS as temp INCREASES. Their purpose is to limit the inrush current.

Few commercial amps employ them as of today.

The point about doubling the voltage on components is simply for over-engineering. There is NEVER any harm in doing it except simply their expense. In addition, higher voltage capacitors have MUCH HIGHER ripple current ratings (check out digikey and search for them, look for low frequency ripple current ratings and ESR) which in the long run always make the components more reliable and less prone to spikes.

These things ALL add up, bit by bit, and increase the lifetime of an amp to 30 years from maybe 15....

I know nothing about electronics, but a couple of months ago I gave the Sony AV receiver I bought new in 1991 to my nephew to use, along with similar vintage Jensen speakers rated at 8 ohms.  Before I gave it to him, I looked inside and cleaned it up a bit, and the filter capacitors looked fine (not swollen or leaky), as did the circuit boards (not dark or burnt-looking).  I found the sound to be pretty good, for what it is.  But from reading here, it sounds like a receiver that old likely has capacitors (and perhaps other parts) on the way out, and when that happens the speakers are probably going to be damaged too.  Unless one does their own repairs, does it make sense to repair something like that when it does go out?  So, use it at your own risk and throw it away when it blows?

The quality of the capacitors used can have a big effect on the longevity. Cheaper caps are maybe 20 years or so (I call it a 'half life' but what I mean by that is half of them that old have failed by that time). Better quality means that your half life is more like 30 years. So it is prudent to consider filter cap replacement in any electronics if they are older than 30 years! 

Capacitors start drying out after 10-15 years especially if used a lot .
ifprice is good buy and have all power caps,and coupling caps upgraded
I allways hav3 it optimized ,you end up witha better amp then new for less then 1/2 replace toowiring and connectors with decent gold copper ,not brass and Neotech Teflon copper wire   

You people are a bit confused. Full of hyperbole, misinformation and bad advice. And I swear a few of you have as well, bad intentions. 
 I am sure at least a few of you will disagree. But your arguments are devoid of ANY, "actual", facts. It is "Heresey", at best, and even that's a stretch!
    Caps? What? Are they suddenly evil? Has ANYONE commenting here ever replaced a capacitor in ANYTHING? Doing it themselves OR even paying to have it done?
 Brian, Do not listen to all the Malarky, Please.
How long is an quality capacitor designed to last for? Why oh why, does everyone that has simply owned more than one decent amp think they understand electronics?

 For instance....The comment above? See #1, 2 and 3 on his "Amp check off list". He has not the foggiest notion of what he is saying. 
1, You CANNOT purchase any electrical device in the USA that does not have either an IR limiter, "The common BUS, Fuse is one type". OR IR limiting is designed into it! .It would be otherwise illegal to sell! "Per any version of the NEC"!
2, Runs cool???? Please feel free to email Nelson Pass that please. "He could use the laugh". That's about the funniest thing I have heard from someone claiming to understand rudimentary modern amplification.
3, Um......Ha ha ha ha ha, Yeah, "We tend to do better than one,  automatically"!. "That would be during the design phase of a product".
     Get my point Brain?
I currently own more Nelson Pass, designed amps than will even fit in a 12' x 12' room in my home. And I am about to put a bunch up for sale.
 I guess no one here talking about Pass amps has ever noticed that nearly ALL of them have "NO", ext. heat venting whatsoever. Heat is your friend in that type of amp architecture. The largest 2-channel he ever designed? I JUST sold mine. An orig. "X-350". It NEVER ran hot. "Surface's never above 118 degree's F."...And if it is ever re-capped? It will sound like crap and probably "begin", to run hot.
 My "Aleph 0", mono-blocks from Pass Lab's did run hot. Maybe because they were attached to the worlds largest transducers playing down, down, down to "Who knows where". But those, "Theoretically". Will double down the ohm load into infinity anyways. OR at least until they melt. "Did that once".
Caps dry out because they have burst. They leak when that happens. They burst because of misuse. Not really from age. "The capacitors built in Mason Jars, and over 100years old from the workshop of Mr. Tesla are still, NOT dry". We are still using his basic design for caps. "Except for the new super caps", "Another story"..
 There is no need to replace nearly any, modern made "Electrolytic" Capacitor manufactured in the last 30-35 years, unless the amp has failed.  Why would one fail, "cap"? Usually either a bad design of cap OR amp. And nearly always they have also been abused. "Like doubling or even quadrupling the Ohm load against the intended design. By NOT hooking it up correctly! By hooking every single component you have, "Plus a few lamps, a fan and a clock". To a single residential 15 amp circuit in which the service breaker that was past it's prime a quarter century ago.....doth reside.
  If you have good gear. Especially amplifiers. Have it fully serviced AT LEAST every five years. Every two if you smoke. Good gear will last you a lifetime IF you take care of it. I have tube amps from the early '50s with the orig. tubes that still sound and run great!
 And If you would like to try one or three of the amps I mentioned above? Let me know and we will work something out. And ALL are recently serviced, guaranteed and warrantied. BY ME! and most are in your price rage I believe. "I should tell you though, I am not a dealer. I am a collector", And a small manufacturer.
You will get out of this hobby what you put into it......Good service is not cheap and depending,. May be impossible to find locally. But there are a "Plethora", Of good shops. Most small, That will do this through Mail-Order. And plan to spend a minimum of $250 having it done. Not counting shipping if you go that route.
 Finally,  "IF, someone say's they will fully service an amp for $50? And it's not a blood relative you trust? Run....."
     Still with me Brian?

These are typically the factors that reduce any electronic device’s life:

1) Inrush current at turn on.
2) Temperature.
3) AC voltage spikes which causes the maximum allowable voltages to exceed for various components.

Sooooo.. pick an amp which:

1) Has an inrush current limiter (lights do not dim when you switch your device on).
2) Runs cool.
3) Components in it are rated at twice the maximum rated operating voltages.

Pass labs seems to be one of the the few exceptions where most run pretty hot (class A) and yet still are very reliable. I can only guess that they must be using absolutely superb components inside (like 105 degree C capacitors) , which may also explain their prices.

My Classe DR3 is 40 years old of Pure 25w in Class A and works real good ;)

No AV piece made more than a couple years ago is a good bet for longevity (excepting Theta Digital)

I am a big fan of Theta, lived very happily with a Casanova for years. Really should not have sold it. Anyway...

Sadly, since HDMI came out, Theta has usually lagged the industry by years. I always worry it’s on the brink of financial collapse. It took what, like 3 years for them to introduce an HDMI ready processor?

I wish this was not true. I was really ready to buy the new Casanova. Supernova? Something like that. << sigh >>

At least relatively, the MRX 720 will be cheaper to replace than a Casablanca will be to upgrade. :)

With quality gear well worth rebuilding 
the capacitors dry out ,
and while rebuilding improve  the design ,most all amplifiers or preamps 
use good reliable average parts ,coupling capacitors many good brands ,for the power supply  there to buy the best electro Lytics , get all1% resistors 
and signal path small values Vishay naked, Non magnetic Tantalum resistors brings natural character in the right areas. And for sure rewire 
Neotech makes excellent Teflon -0 Crystal copper wiring,as well as silver.
your connectors for sure make a difference ,for not much money 
WBT makes a less expensive all Gold Copper text gen for speaker terminals 
and rca, Furutech makes the best gold
or rhodium over copper IEC inputs 
from there there are many tweaks .

I have owned about 50 amps .In my experience things start to go south after 15 years but as the decline
is slow your ears adjust to the decline till about 20 years .

ditto others, it is said that caps last ~20 y, but that is average, of course....initial quality of caps, how hot the amp runs(ventilation), and amount used, of course, all play a role....certainly they can last longer, but when the amp starts having a hum, they are going......also, humidity can play a role, as restistors, as they heat and cool can crack with age, and if humidity gets in there, I think that also contributes to shortening lives....

Great information to consider everyone.  Thank you.

I'm with Erik. No AV piece made more than a couple years ago is a good bet for longevity (excepting Theta Digital).  The Anthem would be a nice upgrade in sound quality over the Marantz, as well.`One of the most disastrous adventures upon which I ever embarked, as far as my marriage is concerned, was me trying to repair my aging Conrad Johnson PV 5. I didn't think to fully test the transformer until after I'd replaced all the caps and several other components. I personally, will never buy used again. The risk is much higher than people think and the opportunity cost is huge as well.

  iv'e bought a used 1990's arcam delta power amp, sounds great and looks mint  .if i   h e a r   a bad sound than i might worry about caps. it has no moving parts and if it's a quality piece usually it's been well taken care of,if not than after 30 years you will see signs of abuse or humidity.if it looks good and mainly sounds good don't worry about it. lexicon's are a great  choice and sounds way nicer than most of today's amps and will pair well with modern dac's preamps and speakers.go for it.

One last thing Brian339. You mentioned you might get height speaker for Atmos later. If you do not want to add the expense for the Atmos amps right now you can upgrade and add them to the Emotiva box later, You do have to send it back for them to add the amps. The amp box has seven amp bays. You can buy a five channel amp in a seven bay box for expansion later. The last two bays would have lower powered stereo amps for the heights/Atmos. Due to shipping cost just have them installed now so you are ready. Worst comes to worst you can power a second room or some out door speakers for now until you decide what to do about Atmos. The Marantz receiver can do all of this without breaking a sweat. 

Now for the two channel. Now or later you would get a two channel preamp with home theater bypass. On the lower end you can go with an Emotiva USP - 1 ver 2 for $1100 retail and $750 eBay. Or on the high end Hegel for $4000. I have the Emotiva. I like that it lets you add the subs to your two channel setup and uses balanced input/ outputs if you want. 
Here is how it works: 
To listen to your system in stereo for music or TV you turn on your two channel preamp and stereo amp. High power great sound and pure as silk. When you want surround sound you turn on you Marantz Pre/pro and your multichannel amp which can be turned on using your 12v triggers along with your two channel setup if you choose. Push the HT bypass button on the two channel preamp and the Marantz controls the volume and sound of your two channel system. You can even program some of the two channel buttons on your Marantz remote so you do not need the 2 channel remote all the time. I love separates. It gives you control of your system. Later you can add a DAC to your two channel system for more better digital sound. That is a whole different thread. If your not into the music or two channel stick to my first response. Also everyone in this chat is correct about the caps on the older amps. Your speakers are very nice and I would be careful about older stuff. If you do by used please have it checked out by a professional before you hook it up. If the caps are bad or the gain or bias is set wrong you can do a lot of harm to your system. $50 can save you thousands. 

Hello,
I can tell you from experience that having a really nice multichannel amp for home theater is awesome, but also very expensive. It sounds like you are trying to get two channel music an surround out of the same system. Marantz is my favorite Pre/pro. You have to realize that it is a processor. Even in pure mode it wants to color the sound in two channel. For now if you want higher end I would look at NAD class D for the center and surrounds. The processor can manipulate the sound to make the speakers blend together. Personally I would go with an Emotiva 5/4. Call them or look at the website and you will get it. You can have 5 high powered channels for the center and surrounds and use two of the slots for the 4 heights/ atmos. No risk because you can return it if you hate it. 

Buy a sugden class A and it can double as a space heater in winter! 😁 seriously though, there is nothing wrong with Marantz. I own the pm14s1 reference made in Japan and it is a terrific sounding integrated that I will never part with. The Sugden I have just sounds different, not necessarily better than my Marantz. 

any thoughts on 'mcintosh' amps??