Just got a new power amp

kijanki

PS Audio S300 is not fully balanced ...

You might want to check the specs of the amplifier here. They certainly reflect those of a balanced amp.

@cleeds   I don't see anything in specs showing fully balanced operation.  

Look at page 5, Fig 1  300AS1 datasheet  showing block diagram.  After balanced input, there is only one path (one amplifier).

https://shop.icepoweraudio.com/wp-content/uploads/2023/02/ICEpower300AS1_Datasheet_2_2.pdf

kijanki

I don't see anything in specs showing fully balanced operation.  

Look here. Big clue:

Input impedance 

Unbalanced 50KΩ
Balanced 100KΩ

After balanced input, there is only one path (one amplifier).

So? You seem to not understand how a balanced amp works.

This amp looks like it's differentially balanced, a perfectly valid approach. This is taken from the data sheet you provided:

Input Stage
The balanced input section provides signal buffering and anti-aliasing filtering. The balanced configuration helps to avoid hum and noise pick- up from poorly shielded cables. An unbalanced input can be obtained by applying a short circuit
between Signal In- and Signal GND ...

Output Stage
The output stage is a full bridge topology with a 2nd order filter, thus the power output on the terminals Vo+ and Vo- is balanced ...
Warning: The balanced speaker outputs are both “hot”  (emphasis added)

@cleeds  It is amplifier with balanced input and not the "Fully Balanced Amplifier".  "Fully Balanced Amplifier" term refers to amplifier consisting of balanced input followed by two separate amplifiers - each driving one terminal of the speaker.

 

kijanki

"Fully Balanced Amplifier" term refers to amplifier consisting of balanced input followed by two separate amplifiers - each driving one terminal of the speaker.

Of course you are free to define terms for yourself anyway you like. But a "fully balanced amplifier" doesn’t require two separate amplifiers. You simply do not know what you’re talking about and your claim conflicts with the manufacturers' published literature.

An amplifier using balanced inputs, balanced circuits and providing balanced outputs is, by definition "fully balanced." It’s as simple as that.