Any comments on DAC directly to Power amp with no

08-18-15: Hgeifman
I am concerned about having a fully balanced DAC running into a fully balanced amplifier and NOT take advantage of the two balanced units. My test should help me decide how to proceed.

Although the L-590AX is described in various places as being fully balanced, I'm not sure that is the case. First, it seems unusual for a balanced amp to provide most of its line-level connections via RCA's, as can be seen in this rear panel photo, including the pre-out and main in connections as you mentioned. Also, the lightning bolt symbols near the speaker terminals, which are presumably intended to alert the user to the possible presence of high voltage, are adjacent to each of the red terminals but none of the black terminals. (A balanced amp would provide voltages on the black terminals that are essentially identical to those on the red terminals, aside from a polarity inversion). Also, in many cases a balanced amp will have a statement on the rear panel cautioning against grounding the negative (black) terminals, which is not present in this case. Check and see if the manual has such a statement; if not, it would cast further doubt on the amp being balanced.

So in the event my suspicion is correct, as George suggested above supplying the amp with a single-ended signal may actually be preferable to supplying it with a balanced signal, since it would eliminate a balanced to unbalanced conversion from the signal path.

Also, if you have a multimeter available you could make some simple measurements to verify whether or not the amp is fully balanced. Post back if you'd like further info on how to do that.

In any event, good luck as you proceed.

Regards,
-- Al

Fully balanced components usually list 2 sets of specs.

08-19-15: Zd542
Fully balanced components usually list 2 sets of specs.
Zd542

That can also be misleading, as if they used an opamp for the balanced input or output of source or poweramp it's very possible that it's not a unity gain stable opamp, so they had to give it some gain to make it stable, which would give different specs as you say.

I've seen it all too many times. A typical example of this is my cd player which has both single ended and balanced outputs, the extra opamp they used for the balanced had gain compared to the single ended output, which bypasses the balanced opamp, therefore one less opamp in the signal path from the single ended output.

Same went for a very well known famous high end poweramp $$$$K which I was repairing, the input went though an opamp first for the balanced which had gain because it also was not unity gain stable, and the single ended input was after the opamp. I laugh to myself when owners say the balanced sound better than the single ended on this amp, I don't have the heart to tell them because they were told by someone to use it that way for better sound.

So the safe bet for the best sound is always use the single ended inputs, unless you run 10mts of interconnect then balance connection will only have an advantage in noise/hum not sound quality.

Cheers George

Good points George! I can't see the Opamp solution being ideal for sound quality. A genuine differential balanced circuit would seem a better choice if someone is seeking true balance components. Still not a sure guarantee it will necessarily sound better than a well implemented single end circuit.
Charles,

The Nuprime Dac-10 might be nice. I say this because I'm using the phenomenal IDA-16 integrated and LOVE it, not because of the new review out in Absolute Sound that my buddy told me about. I haven't read it as I've stopped getting the audio rags years ago. They're all rubbish.