DACs that do well without a preamp

I find the "a preamp makes it sound so much better" a little confusing.  My only conclusion is that many people try this without doing any homework.

First - there's a huge question: how does the DAC perform volume control?  Volume control, in general, is the single largest source of sonic impairment in a preamp  (IMNSHO, but i have done a lot of actual research on this). So if you eliminate the preamp you are shifting the major sonic coloration from the preamp to an ancillary function of the DAC, which often is **awful** but occasionally is outstanding.

As an over-simplification: the only DACs to truly do volume control well are based on 32-bit, sigma-delta DAC chips, that allow for volume attenuation in the digital domain but, do to their 32 bit architecture, do not suffer this (significant) problems that most digital volume control does. If, for example, you use your PC or streamer to do this, digitally, before a regular DAC, forget it. The distortions are huge and built right into the math.  While i explained the generic result i think the only common chip like this is the ESS Sabre 9038.  Being 32 bit you can do the digital volume math, have all the truncations and still be left with more than 24 bits of resolution.

Other methods of volume control, that are cheap, and suck, include vary-int he feedback loop of an opamp, or using a buffer and a IC based resistive network. None of these are designed to be awesome - just convenient.

I use one DAC with the ESS chip directly (sometimes) and it sounds great.  Its only failing is that its analog buffers don't drive my cables as well, and i think i can hear the lack of weight -- but also the tiny little increase in transparency that comes from eliminating one stage with no other changes (except the aforementioned output drive capability and stability).

So - to answer this you really MUST do some homework not just on the chip and volume method but on the analog stage.  Or guess. Or listen to random people's thoughts which is basically guessing.

@cheeg

It can't be the quality of the volume control ALONE, or the better companies would have fixed this flaw. Is the issue in the interface to the power amp (eg. an impedance mismatch), or is it a failure of the analog stage to accurately amplify the signal to line level?

You hit the three nails right on the head.  And i have looked at many circuits and they are not "fixed". dont under estimate how much the volume control method impacts sound. I just spent 3 years in my lab inside pandora's box. And an output (analog) stage that measures really well may not sound quite as good (let's not go here, OK :-) ?)

@mitch2

Some quick answers:

1. No i have not listened to the unit you mention, but i have experimented with it myself. It does have one major limit- which you allude to below. The contorl must be very noise free

2. Paul’s quote is irrelevant for the line output stage. His comments apply to LSB resolution of the DAC itself

3. Disagree --somewhat -- with Ralph’s vast over simplification. Keep the analog and digital sections independent but the two analog sections may be the same. That said, i would NEVER run a line stage or DAC output analog stage at the +5V or +3.3V provided to most DACs so in a practical way, fine.

I'll add that I probably spend more deign time on power supplies than on circuits, so the concept is good.  Yet this all comes back to "is it designed right"?  if if not, why does it work when run into a preamp - the problems don't just vanish you know.

... and yet it is irrelevant if you understand the topology of any DAC. There is an internal output stage (line stage) and it drives the preamp. It may be very simple (even the output of the DAC) but its there, and its characteristics don’t change.... until you add the volume control and then you are back where i spent my time in a previous reply.

As to Ralph’s last quote - i said that above. Maybe you didn’t follow. but this is going nowhere fast. I stand by everything i said. Its the output / volume configurations and the devil is in the details.