Optimizing Digital Volume Control

The fact is that no preamp will most of the time be better than using an active preamp. A transformer-based linestage (TVC) is one option. A DAC with really good volume technology (not like an active preamp) is another option. Both of these require that the DAC have a strong output buffer. Op-amps need not apply.

The best overall solution IME is to use a combination of volume control with a TVC or; DAC (with exceptional volume control technology) or discrete gain settings and a limited amount of digital volume control The ideal thing is to use up to -10dB of digital volume decrease and no more than that. This way the digital part can be the remote controlled part and the fixed volume can be manual.

So, there are these requirements:
1) sufficient drive from the DAC
2) Passive TVC or
3) DAC with discrete gain control or
4) DAC with reference voltage volume control

Steve N.
Empirical Audio

I was firmly into the no preamp camp (used the volume control of my msb dac) until I tried the arc ref5se. No comparison - preamp is back. Not cheap - extra set of interconnects, power cord - the works. Bottom line: forget theory and dogma and trust your ears. In my experience, only very high grade preamps will beat no preamp. But they do.

My DAC has a digital volume control and I've tried running it straight to my amp. It is very clean and musical, but lacks dynamics. When I put a pre amp back into the line, it was still clean and musical, but I got the dynamics back.

Let me qualify my comments by stating that my conclusions are a combination of about 6 months of listening and many years of engineering studies. I listen mostly to classical music, so this may be coloring my assessment. My speakers are Magnepan 3.6 and Willson CUB2s (I alternate between them).

During my brief journey so far I had the opportunity to work directly from the CD through an ARC LS2, Audible Illusions M3A, McCormak LD-2, and through the Hegel HD20 DAC (for the past 3 months). Today I can say with confidence that with the equipment I use, without the preamp, using digital volume control provides better result to my ears. I started with the expectation that a preamp is a good idea (based on the majority opinion), so my prejudice was to confirm that belief. But as I went through my music library I couldn’t ignore the fact that the sound without a preamp is better.
It so happened that this conclusion is aligned with sound engineering principles. The modern DACs are incredibly good. Their dynamic range and noise figures are amazing (to an engineer). This is a result of advances in semiconductor technology, which makes it practical to build such works of art at a low price. For example, Hegel just came out with a newer version of the HD20 that utilize a 32b DAC with a noise figure of -145db. With such a device I doubt an analog preamp (at least at the same price range) can compete, even up to a 50db volume range.

BTW, I contacted Hegel regarding this observation and Anders wrote me back the following: “At the top 50% it (the HD20) still outperforms our P4Amk2, that used to be our 4600 USD pre amplifer”.

Oferi, with all due respect, I came to the same conclusion with the caliber preamp you tried. You need to move way up the preamp foodchain to get an improvement over no preamp. So no preamp offers superior price/performance any day of the week, and will be the best architecture for the majority of systems.

However, in my experience, if you want the best of the best, you need to pull out the checkbook bigtime and get a VERY good pre. Nine out of ten "ultra high end" guys (six figure systems and up), will confirm this.