Which DAC is better?

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.

Having heard the extraordinarily good audio quality of 24 bit material on the Arcam FMJ D33, and given that the Sim Audio does not support 24 bit, then my cash would go on the D33.

Better... they're DIFFERENT, but only your ears can really decided what is better...

Personally, I would say the MHDT Havana is better, but that's because I love the way it sounds. Non-oversampling, tube output, etc.