Matching fully balanced with unbalanced.

Sure. But its likely that the amp, even though equipped with an XLR connection, isn't actually processing the signal fully. If the equipment supports the balanced standard (and in high end audio most of it does not) you will run into a buzz problem, although that is easily solved. If the equipment doesn't support the balanced standard, you likely **won't** encounter buzz. I know this sounds counter-intuitive, but that's how it is.

other words, run balanced as far as u can should be beneficial you think? ...  yes, unbalanced amp is equipped with XLR inputs.  

I think listening is more important than topology.

While a true balanced interconnect is less susceptible to noise, a fully balanced amp/pre are not by themselves going to convince me to spend more.

I think all XLR interconnects are true balanced, rather components could be not even if they equipped with XLR connections.... I wasn’t trying to go chipper on my preamp..i just try to understand if it beneficial to go balanced as far as I can in the system chain if I have unbalanced amp at the end anyway. 

surfmuz OP
Hi, using Fully Balanced VS Unbalanced Preamp between Fully Balanced Source and Unbalanced Amp with all XLR Interconnections including amp.... Does it wort it or not ?

First off, you got to ascertain by looking at a circuit diagram of the input and output of the equipment in question.
To see if the balanced input or balanced output is "just a balanced opamp" used to give balanced output or inputs.
Because then the rest of the amplification circuit is probably SE (single ended).
If this is the case then the SE (single ended will sound better).

And if it’s is truly a "true balanced circuit throughout" from input to output with no opamps doing it, then it’s only got a noise advantage over SE if the interconnects are >5mts.

A very nice Classe DR** poweramp had just this opamp for it’s balanced inputs and the SE inputs did sound far better.

Cheers George

In my experience only listening will really tell, as it also depends *how* the balanced is IMPLEMENTED in the source equipment(s). 

This unless some very long IC connections will be the case and RF issues adding to the mix. 

With my equipment (all ML) feeding PASS poweramp, and having tried unbalance, balanced *always* by tiny SQ improvement won the day.
This, mind you, with no IC longer than 5' and the shortest less than 1'.

At the same time folk with diffent equipment and set up, having different synergys, will tell you, unbalanced will improve air and spaciousness, as oppose to a more dence and firmly focused image presentation.

Long story short, only testing and listening will tell it, is my learning.
Michélle 

Of course testing and listening that for sure, but could any body throw scientific base under this topic?

I prefer the single outs/ins on my system. Long cable runs are not an issue for me, and really the primary reason to run the “balanced” outs/ins is mostly this. Also, as mentioned, few systems are truly “balanced” anyway...

Not sure the science of your question was not answered already...? 
If *balanced* is 'pseudo balanced' i.e. achieved by opamp implementation as compared to 'fully balanced' implemented by two seperate strands of amplification within one source unit, the notion is that fully balanced is superior technically to a 'quick fix' opamp implementation. 
So, if the equipment is not a fully balanced design (looking at the design diagram was already mentiond) THAN it will by deduction appear to keep the opamp out of the source line AND USE THE SE (single ended) connection. 
Drilling further into the science of whether the addition of on opamp is beneficial to sound quality can be answered by listening, what has been mentioned. 
BTW, that opamp chops a full audio sign-wave into a negative and a positive, so it's up to the beholder to decide whether this is of no import to the signal further passed down the line. 
Again, if the final stage the poweramp has a pseudo balanced input option, the use of this also involves an opamp to first combine the two halve waves, ahead of the actual poweramplification stage(s). 
Common sense, at least, suggests that this again will not lead to any signal improvement but rather to a degree of its deterioration. 

Not sure this fully will answer the question regards any scientific proof etc.. 
To do THAT, a signal analyser would need to be called for plus engineering experience in explaining the results generated. 
M. 

surfmuz OP7 posts05-23-2020 3:45pmOf course testing and listening that for sure, but could any body throw scientific base under this topic?

Sure simple, what comes out of 99.9% of hiend poweramps is SE (single-ended), the speaker terminals are + positive and negative is at ground potential.

Cheers George.

BTW, that opamp chops a full audio sign-wave into a negative and a positive,

Huh?? No it doesn't. An opamp has two inputs, inverted and non-inverted, and otherwise is a DC coupled amp with very high gain. for audio purposes, to control the gain and allow the opamp to operate in a linear fashion (otherwise the output tends to spend a lot of time at one rail or the other), feedback is applied. The resulting gain is thus then the ratio between the input resistor in series with the inverting input and the value of the feedback resistor. It does not chop the signal or anything like that- the output is single-ended, and in phase with the '+' input and out of phase with the '-' input.

Tnx, atmasphere...full and argumentative explanation. 
 I knew the topic isn’t easy... but consensus should be reachable:) ... However, Physics is not Psychic. :)

.i just try to understand if it beneficial to go balanced as far as I can in the system chain if I have unbalanced amp at the end anyway.

The answer to this bit is 'yes.'