DACs don't have transformers, but depending up on the chip, they produce different kinds of high-frequency garbage and noise. I wonder if that can affect the audible range in a similar vein to how ultrasonic stuff in audio transformers seem to do. So I wonder what are differences (ultrasonic junk) between AKM4393/96/99, SABRE, PCM1704 - three chips that I have heard which sound very different. Especially the SABRE. But we will never know because SABRE supposedly signs everyone to an NDA, and no one who hasn't can see their spec sheets.

Also that noise needs to be filtered. There's the question if that filter will cause an audible affect.

I can't comment on the others, of course (even though we've tried them), but the AKM4399/6 are the most like R-2R in terms of output noise, due to their internal switched capacitor filter. It's one of the reasons we decided to go that route.

Of course, R-2R is even better in terms of noise, since they don't have a master clock at all, though (depending on the actual IC used) they can have glitches between the steps, which may require things as simple as a notch filter or as heroic as a ultra-low-distortion sample and hold to eliminate.

DSD is by far the worst, since it's really just noise anyway. On a good scope, you can filter the HF out of a DSD signal and see the audio directly.

I can't comment on the others, of course (even though we've tried them), but the AKM4399/6 are the most like R-2R in terms of output noise, due to their internal switched capacitor filter. It's one of the reasons we decided to go that route.

Of course, R-2R is even better in terms of noise, since they don't have a master clock at all, though (depending on the actual IC used) they can have glitches between the steps, which may require things as simple as a notch filter or as heroic as a ultra-low-distortion sample and hold to eliminate.

DSD is by far the worst, since it's really just noise anyway. On a good scope, you can filter the HF out of a DSD signal and see the audio directly.

That's interesting. So maybe I'm not insane in believing that of the DACs I have heard so far, these two (and the DCX2496, but that one is very lacking other technicalities) sound the most similar in having a natural timbre. (My time in the last few days has mostly been between the M7 and Gungir.)

Most other sigma-delta chips have a raspyness / grain / un-liquid quality of varying extent. SABRE is nasty. NAD M51 with their proprietary / mysterious PCM - PWM approach (sounds like sigma-delta with a twist) is slightly weird, but not annoying.

DACPort LX also use the AKM which I like better than the ODAC.