Uprgrading my Metrum Octave DAC

1) DC offset - almost none
2) common-mode noise - common mode noise is reduced in a diff amp stage
3) difference in amplitude between + and - signals (impossible to make these identical with active circuits) - hello current source
4) isolation of ground between DAC and amps - entirely different topic

You're right in that it's not perfect. You should also realize that none of this is perfect. Especially a transformer!

Transformers are for isolation and impedance matching. They are inefficient and sloppy. They are not extremely linear.

I've heard good music coming through a xformer, who hasn't. I just would not use one unless I had to.

Let's just agree to disagree. From a design methodology standpoint I prefer to keep nonlinear devices, like transformers and capacitors, out of the signal path, and bias devices in their linear region.

Here's a little review for you:
http://www.ecircuitcenter.com/Circuits/BJT_Diffamp1/BJT_Diffamp1.htm

If you bias this with a current source, it's almost perfect. Certainly as perfect as any transformer.

Balanced in, balanced out, and you set the bias voltages so you bias your next stage, which can also be fully balanced. Nothing new.

RM

Steve N., I ripped several hundred CDs (using XLD) as FLAC files. Can they be converted to WAV files, or do I have to rip them all over again? thanks, Matt

In other matters, does anyone have any DAC suggestions?

01-02-13: Linaeum66
In other matters, does anyone have any DAC suggestions?

Linaeum,

I very much apologize for the thread hijack. Didn't intend to do it and won't discuss the "other topic" any further with Steve on this thread.

I have the Octave with a Audiophilleo driving it. Just like you. I would not try to improve it unless I could demo the pieces in my own system for a few days at a time. I find reviews to be almost useless, unless they are way negative, then it's pretty safe to stay away.

Personally, I would like to try Steve's OR5 via SPDIF into the Octave, if I was to try anything. But this would not solve your two-box issue.

RM

Matt - you can convert all of your FLAC files to .wav using dbpoweramp on PC or XLD on Mac.

Steve N.
Empirical Audio