Single Ended vs Balanced Output Gain

Make things simple,what I talked about  is real XLR amplifier port and RCA port.

It is real circuit inside the machine.

Now on first time,I really  feel the taste of  the  amplifier, the tone of the amplifier is so important,which I can not change anything,even the cable.

My pre is Rega Cursa 3 ,or Audio research LS25 MK2

Cursa 3 is RCA only

LS25 MK2 has XLR or RCA

My power amplifier is Audio Research VT100 MKIII, or REF 75se

VT100MKiii have rca and xlr

REF 75se is XLR only

When I listen to vocal Jazz,the only good result is 

Cursa 3 + Vt100 MKiii with rca connection.

I try rca to XLR cable with VT100 MKiii XLR port or REF 75se

the sound becomes different.

The only ok result is LS25MKii + REF 75se,but not good result,the sound is much modern,the jazz I listen is not like the jazz in the nigh club, but a group youth people dancing  on the stage. 

That let me think of conrad johnson fans,they stick to rca connection and do not affect they enjoy the music. If some one said the XLR is so advanced,It is nothing to me here. I can not listen over 1 hours with XLR connection while I can listen as long as I have time with  Cursa 3+ VT100 MKiii RCA connection.

My speaker is focal 905,which is not expensive,but very very good.

In my case, I listen vocal Jazz 99%, I want a low voice most of the time as I do not want to disturb kids learning.

I want the singer voice outstanding among all sound.

Never mind that the recording was made using balanced connections!

The most important thing I forgot to mention is that my RCA pre get perfect sound in my point of view,if I changed the pre, the sound is different. I also try RCA to xlr cable, the sound is also different.I will stay with this pre,that's the reason, and this pre does not have xlr port.

I know for sure XLR system get good sound, and get big sound , (I mean the sound get spacious) and get high,mid,bass in balanced. But in reality, it won’t win in all situations.

In my case, I listen vocal Jazz 99%, I want a low voice most of the time as I do not want to disturb kids learning.

I want the singer voice outstanding among all sound.

So in this case, definitely go RCA connection.

I gotta do this.. I just gotta.. I always knew it was the best way and can remember a guy doing this 25 years ago in El Grove CA. He made tonearms and carts for radio stations. The same kind of set up was used for R2R too. It's actually better than direct head playback, though I suppose you could add the XLR to the tape head covers too, just like RCA DHP is.. Kinda last on the list these days, Vinyl first then maybe magnetic media again.

In Retirement, TIME flies fellas.. WOW.. I gotta keep up.. LOL

Regards

Once you hear a balanced line system operate properly by supporting the standard, you never want to go back.

I agree! See below article.

https://www.ranecommercial.com/kb_article.php?article=2107

Is this typical on pre and amps that have both Single Ended and Balanced Outputs?

@post2338  @cleeds 

It really should not be that way, and this statement

A differentially balanced design will yield a 6dB higher output than it will single-ended.

Is false. But there is an important nuance/ caveat! The way balanced operation is supposed to work is that the signal travels in a twisted pair inside a shield, and the shield is only used for shielding (unlike in an RCA style cable where the shield is often part of the signal return).

In the old days and still to this day transformers are used to drive the balanced line cable. The transformer doing this is driven by the source (perhaps a preamp) and its output is a simple secondary winding without a center tap or any other complexity (so its output is exactly 2 wires). Its merely connected to pin 2 and pin 3 of the XLR connection. Pin 1 is ground and is not part of the transformer connection at all.

Now a transformer can drive single-ended as well as balanced. All you have to do is connect pin 3 to ground (pin 1 of the XLR) and the single ended connection is ready to go. But you may notice that the signal level has not changed at all- its still the same transformer with its same signal.

The reason you see this 6dB increase talked about so often is that the circuit driving the XLR output doesn't support the balanced standard, and is likely just two single-ended outputs that are operating out of phase with each other. So the single ended output is simply one of those phases (usually the pin 2 connection) and if you add the second phase for a balanced connection you double the voltage- and there is your 6dB.

That isn't how its supposed to work, but most high end audio companies with balanced line products either choose to ignore the balanced line standard or are ignorant of it. I don't know which. At any rate, when this '6dB thing' comes up, you know right away that the circuit isn't supporting the standard.

The standard has two outstanding attributes. The first is because it ignores ground, ground loops should not be able to occur. The second is the interconnect cable won't be able to have a 'sound' like audiophiles are so used to hearing with single-ended cables; it allows the system to be more neutral, more musical. Ground loops create noise and can buzz when severe; with that property lost it won't be as musical! The same is true of cable immunity.

So its a real shame IMO that the balanced standard gets short shrift in high end audio. Its also why you hear so many people talk about how single-ended might actually be better, which it isn't. Once you hear a balanced line system operate properly by supporting the standard, you never want to go back.

RCA vs XLR,the sound is also different. The mid sound in RCV connect will be outstanding, while XLR high,mid,low will be even.

I try to connect RCA pre to XLR amp(use RCA to XLR cable ),and the sound is like some mixed,finally I give up that cable. 

My opinion is that choose all XLR or all RCA and will give you best sound.

For me,I am really interested in vocal jazz and I think RCA system is more suitable as the mid vocal is just in front me while all  music instruments are step behind,which is really like the small band in the nigh club. I love it.

A differentially balanced design will yield a 6dB higher output than it will single-ended.