For those with doubts : look at Taskmanager and the Performance tab. Isn't it so that it completely stalls when a track is loaded ? why ? there is no reason to. Not according the priorities, and not according the affinities (which processor core is allowed to do what).

I am also on W7 and I can confirm that there is no problem (similar picture). I do have nVidia driver active, however it looks like W7 can handle it easy. I did switch to Standard VGA but this does not yield any significant improvement in Latency. So I switched back to my full HD resolution mode and I like it a lot!
Cheers, Eric.

I’ve just gotten around to doing something that I’ve been meaning to do for a while – comparing the effects of QAP on my Esoteric D70 vs. my Pacific Microsonics Model Two.

The D70 uses PCM1704 converters (in dual-differential mode) and still oversamples at 176.4KHz (I believe it’s 2x oversampling, using its FIR filter). The Model Two uses custom, discrete, full-ladder converters and is non-oversampling at 176.4KHz (I believe).

The D70 results first. With no QAP (i.e. straight 16/44.1), XXHE through the D70 sounds great. It’s a beautifully laid back presentation and about as un-digital as you could imagine. If this was the last DAC I ever had, I’d be pretty satisfied with this sound.  However... engaging QAP simply kills the sound. The bass loses its tunefulness – it becomes fat and lumbering. The ambience and twinkle in the top-end is gone. If anything, it sounds like QAP increases smearing. Overall, it reminds me of why, in the past, I’ve never liked the effects of any upsampling.

On to the PM Model Two. The first thing that hits you is the shear visceral impact of the sound – this thing has an output impedance of only 20 Ohms and will drive a bloody tank! (If you ever get a chance to hear one of these things... do it!) With 16/44.1 material, the sound is stunning. But... with QAP, it simply gets better! Everything becomes more focused. And the dynamics... well you’d better have equipment that can handle what’s thrown at it.

QAP through the Model Two is the second best sound I can get from digital. The first is from original 24/176.4 files recorded on the Model Two itself (e.g. the 24/176.4 RR files). Interestingly, these 24/176.4 files don’t sound very good on the D70, suffering the same sort of effects as 16/44.1 files with QAP.

In conclusion, I believe QAP needs a 24/176.4 NOS DAC to do its magic...

Mani.

Ok, just spent a few hours on this, but there is no way I see what you see. Not by SPL measuring test tones, not by SPL measuring music, and not by looking at test tones at the scope. But maybe to keep in mind : I can only compare with the other means of upsampling, or no upsampling, and, my DAC doesn't filter either way.

It should -said softly- be the conclusion that when your DAC is allowed to filter effectively itself (read : it hasn't been pre-done so now that math in there goes along with it (as how I estimate it works !)) it "filters" everything down with some 6dB ? hard to believe of course, but theoretically possible.

I can imagine it depends on the music, and for testing SPL with music I used the Yellow Submarine track from the original Yellow Submarine album. Just the first 20 seconds or so. Maybe you should try that one as well, just in case.
If you don't see it happening there, you might mention to me what you used to see it happening. Then I can check that too.

Peter