DACs that do well without a preamp

@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 :-) ?)

@itsjustme 

As an over-simplification: the only DACs to truly do volume control well are based on 32-bit, sigma-delta DAC chips

Have you heard or considered the Cees Ruijtenberg (Metrum then Sonnet) DACs that control volume, i.e., change the output voltage, by changing its reference voltage?

I find the "a preamp makes it sound so much better" a little confusing. 

Many (but not all) who have listened to the comparison between DAC-direct to amplifiers vs. using a good quality active preamp, and also the comparison between using a passive volume control vs. a good quality active preamp, report that having the preamp sounds better.  That has also been my opinion after multiple comparisons using passive volume controls and also using DACs that control the volume internally.  Although there are obviously subjective preferences at work, as in all of this hobby, IMO, the active circuitry in the preamp (even a unity gain buffer) helps control impedances and interconnect effects, and also mitigates potential demands on the source power supply.  Below are a few observations posted previously here:

DACs are significantly more sensitive to power supply changes and noises than preamps. When an output stage struggles to drive a complex load, it is the power supply feeding its output stage that sees these changes. If this occurs in a preamp, it has little effect. But that same situation, when applied to a DAC, has very different results indeed. Small changes in power supplies have big impacts on sound quality–especially jitter. - Paul McGowan

in support of the previous quote: 

Now of course such a line section could be built into a DAC- but then you have the issue of if you ever want to improve the DAC or the line section, you have to replace both (and its often not a good idea to have a DAC and line section run off of the same power supply). DACs are notorious for going out of date; this is a very real issue. - Ralph Karsten

and

I would expect other factors to be at play in many cases, depending on the specific equipment. Such as better sonics from the source component when its volume control is set at max than when it is attenuating the signal; differences in ground loop effects (which can affect low level high frequency noise and consequently “background blackness,” in addition to potentially causing hum), differences in impedance relationships; differences in sensitivity to cable effects, especially if a long run to the power amp(s) is necessary; - almarg

and finally, relative to passive vs. active preamps:

The reason an active line section can sound better than a passive has a lot to do with interconnect cables. Passive controls have poor output impedance- usually quite high, which allows the interconnect cable to do its worst mathematically speaking. - Ralph Karsten

@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.
 

LUMIN X1 utilizing Leedh Processing going direct to amp is very, very good.   I also have a Mola Mola Makua preamp with DAC.   In initial testing, I slightly preferred to utilize the Makua preamp volume control vs the Leedh Processing user optional volume control feature for the X1, but I have not revisited testing that.  I really llke Leedh and applaud LUMIN for including it at no extra charge for the X1.  The newly released T3, as well as P1, and prior T2 also include Leedh.  Early reviews of the T3 are positive and list price in US is just below $5,000.  

Hey @mitch2, that is what I said:  "A good pre amp just sounds better"

and @azwill I have tried my Tambaqui directly vs through my Audionet Preamp and it is much nicer through the preamp.

Happy Thanksgiving Everyone!