1x Oversampling

The sound is open, 3-dimensional, dynamic, natural, smooth, engaging. I have an AN 2.1x balanced DAC (also a Wavelength Audio Cosine DAC in my headphone system, uses the same concept). Best digital I've ever heard. Nothing I don't like except perhaps that there are two boxes.

Do a search of the author Carolus at Audioasylum in the digital domain. He's got pretty much every nonos dac manufacturer listed.

I use the Nixon and the sound is great. But, I should defer my opinion until I've heard some more venerable dacs in my system.

I agree with Budrew right down the line. I've owned the Audio Note 3.1x Balanced, and recently upgraded to the 4.1x Balanced Signature. "Natural, smooth and engaging" is a common thread that runs through all the descriptions I've read of the current non-oversampling AN DACs, and I've heard it even in their entry-level DAC Zero - the one that convinced me to buy into the AN lineup.

I'd add to that list of qualities a sense of "you are there" realism, and bass that breathes like it does in real life. There seems to be much less of an electronic flavour to the sound compared to other DACs. Compared to either of the AN DACs, the SimAudio Nova in my living room system sounds sterile, bleached and artificial.

Are you sure that it's all just due to "zero over/upsampling", and not overall design? Some years ago there was no digital frontends with upsampling available, so they were supposed to sound better just because of that?

Dmitrydr has a point. It's not solely the zero sampling that makes the AN DACs and others sing. It also must be the use of vacuum tubes and transformers plus overall system design. I've heard it said that the transformer-based AN DACs are uniformally better than the non-transformer-based models. In fact, the non-transformer-based 3.1x got the boot when the 2.1x balanced was released since it was clearly better for less money.