Optimizing Digital Volume Control

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 For example, Hegel just came out with a newer version of the HD20 that utilize a 32b DAC with a noise figure of -145db.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.

Like I said, the output of the DAC must be low-impedance with a lot of drive capability and then no preamp can beat it.

It just makes engineering sense. The more stages you add, the more noise, compression and distortion gets added. Less is more. If the output stage of the DAC is as good as any uber-expensive preamp (including power delivery), it will beat it.

Steve N.
Empirical Audio

This seem to be a popular topic nowadays since quality of DACs keeps getting better.
I can agree with Edorr and I can agree with Oferi. In my case and in my system where I run esoteric K-01 direct to Krell 302E, the use of ARC 5se did not bring the desired results to justify its price with extra ICs and power cord, the esoteric direct to amp sounded more refined with equally great dynamics and timbers. But I may agree that using ultra high end pre-amp ( tube or solid state) can result to the better sound. But in case of my system I will need to spend another $20K to achieve this. Instead, I can spent around $5k on a great ICs that will highly improve quality of the sound when running direct.
The important factor to the whole approach ( NO Pre-amp) is to have high quality DAC were its output impendence will match input impendence of the amplifier.