Which DAC is better?

Easy, Arye QB9.

Moon DACs are generally excellent - but that's their top of the line stuff. I just can't believe they would make their entry level sound any good.

Arcam should be taken out and shot for using words like "super USB" - I believe that's enough of a reason to avoid that DAC. Just think, a word like "super" has so much potential -- super coax, super Toslink, super FET, super bipolar, super feedback, super balanced, super Ethernet, super transformer. I suppose when a company runs out of design ideas, it could start adding "super" to everything in order to distinguish its mediocre product.

Chesebert - Is your assessment of the Moon DACs based on having heard one?

Sfar,

I have only heard their top of the line 750D (by itself, without comparing to my own or other DACs). I have not heard their entry level, but I can only assume it (I know I shouldn't) to be of significant lesser quality.

Any chance you can audition both DACs? QB9 does require some computer knowledge (non-trivial for high-quality USB sound) - I am sure your ayre dealer will be happy to walk you through setup procedures.

What about the W4S DAC2? a nice contender.

Some corners obviously had to be cut from the 750D to make the 300D (figuratively speaking, as I don't know if they share anything designs-wise). Obviously it won't sound as good, and nor should it. But that doesn't make the 300D or even 100D uncompetitive in their respective price range. IMO Simaudio has always had a great sound quality per dollar ratio, from top to bottom. The presentation may not be everyone's cup of tea, but what is?

Simaudio is easily worth considering. I liked the Rega DAC more, and for a bit less money, but the Simaudio DAC is easily an excellent piece of gear that should be auditioned if you have a dealer reasonably close IMO.