Uprgrading my Metrum Octave DAC

"Which DACs do you know of that are capable of doing this? I guess you just need a DAC with the right output impedance, why do you need balanced cables though?"

Any DAC with low output impedance can be used, lower than 50 ohms is good. If you drive the music from a computer, then the software player can control the volume. The problem with using most DACs line-out and controlling volume using software is the danger of having max volume and blowing up speakers. As for audio quality, as long as you use a max of -10dB and no more, the sound quality will not be impacted. This means using DACs with variable gain. The danger of speaker damage is still there. Therefore, I dont recommend this technique.

One DAC that you can drive line-out and actually control volume on is the Overdrive SE. This uses a digital volume technology that does not change the data. It changes the reference voltage of the D/A. The advantage of this is that it adds no actual parts to the signal path and changes nothing in the gain stage when the volume is adjusted. The THD actually decreases as the volume is lowered, unlike any other volume technology. This volume controls all digital inputs, so it can be used with computer or Transport.

Steve N.
Empirical Audio

Steve,

I won't debate what your transformers sound like since I have not heard them. Knowing what I do about you, they probably sound awesome. I will say that transformers and extremely low distortion are typically exclusive. And, it's hard to imagine much "new transformer technology" when it's still just coil A energizing coil B. (and all the issues with that) (and there are plenty)

As far as not being able to do true balanced topology with solid state, I'm not sure why you take this stance. Every differential amplifier stage is true-balanced by default on both the input and output of the topology.

Lastly, digital volume attenuation is hardly "new." Yes, there are methods of accomplishing this with technically no distortion. To me it's all unnecessary and yet another way to have your bitstream modified via DSP and I have no interest in that.

I'm not saying any of this sounds bad or is "wrong," I'm just more of a purist when it comes to digital manipulation, as in I want none at all if possible.

RM

"Every differential amplifier stage is true-balanced by default on both the input and output of the topology."

In your dreams. Most good balanced output stages are either tube or discrete, so there are several issues that make them imperfect:

1) DC offset
2) common-mode noise
3) difference in amplitude between + and - signals (impossible to make these identical with active circuits)
4) isolation of ground between DAC and amps

A good transformer solves all of these and makes the amps sound better in the process.

"Lastly, digital volume attenuation is hardly "new." Yes, there are methods of accomplishing this with technically no distortion. To me it's all unnecessary and yet another way to have your bitstream modified via DSP and I have no interest in that."

You are not getting it. This is not DSP. This is not software. This is not even a digital chip somewhere in the signal path. This is something entirely different. This is control of the D/A reference voltage. No modification to the digital stream. Nothing else like it.

Steve N.
Empirical Audio

Steve N., you mentioned that WAV files are superior to FLAC files. Can you explain why ?

Mabonn - I can only speculate why they sound inferior to .wav.

I suppose it must be due to the real-time behavior of the CODEC software in the computer. Statically, the data is not changed, but somehow when these compressed formats are played dynamically, it changes things. I have heard it over and over in different systems.

We can debate this until the cows come home, but that is the experience I have had. Also, all of the partners I have had at RMAF shows had the same experience.

Steve N.
Empirical Audio