garym;611709 Wrote: > hmmm, not sure about introducing jitter (jitter is about the timing of > the packets as far as I understand). This might be interesting reading > (I realize that this is the company's info, but the benchmark DAC I-USB > gets good reviews; mostly just a starting place for a little bit more on > USB DACS): > > http://www.benchmarkmedia.com/dac/dac1-usb > > > Also from their website (again, I'm not suggesting this is gospel, just > interesting -- and I do own a Benchmark DAC I, but an older model where > I'm using S/PDIF for connecting). And note the last sentence below. > > ============================== > Several tests have been performed on third-party, USB-to-PCM converters > to determine which technologies are bit-transparent, as an ideal > USB-to-PCM converter should be. Native USB audio devices, like the DAC1 > USB, have been found to be bit-transparent. Native devices are defined > as those devices which use the native USB audio drivers, versus > special, custom drivers. All non-native devices tested were found to > NOT be bit-transparent. > > > The Benchmark DAC1 USB is unique in that its native USB audio support > extends to 24-bit operation at sample rates up to 96 kHz (with fully > automatic sample rate transitions). All other native USB devices > tested, including 'high-end' digital-to-analog converters, are limited > to 48 kHz, 16 bit. We have not been able to find external USB interface > that delivers the same level of performance as the interface that is > built into the DAC1 USB. 24-bit capability is essential even when > playing 16-bit material. The 24-bit capability prevents truncation in > the computer caused by computer-based volume controls. > > > A common problem with USB audio is the presence of pops and clicks. The > DAC1 USB is also unique in that it is immune to these pops and clicks.
Being bit perfect has nothing to do with being jitter free. A stream can be bit perfect and have lots of jitter. Nothing against Benchmark, but they do a disservice with marketing implying their DACs are immune to jitter. It simply isn't true, and in fact all digital audio has some jitter - you can't eliminate it entirely. What you'd like is to reduce it to very low levels. The Benchmark statement above about native drivers is also very nice, but not so relevant. Yes, asynch USB units that go up to 24/192 need special drivers, but who cares if they work well? That's the reason for asynch USB, as the idea is that if you let the clock of the DAC control the data flow, and not the clock of the PC (as in most USB implelmentations)you will get less jitter. General reaction seems to be that asynch USB is implemented very successfully in many devices now on the market, and for hi-end audio it is becoming the preferred implementation. -- firedog Tranquil PC fanless WHS server running SqueezeServer; SB Touch slaved to Empirical Audio Pace Car; MF V DAC3, MF X-150 amp, Devore Gibbon Super 8 Speakers; Dual 506 + Ortofon 20 (occasional use); sometimes use PC with M-Audio 192 as digital source. SB Boom in second room. Arcam CD82 which I don't use anymore, even though it's a very good player. ------------------------------------------------------------------------ firedog's Profile: http://forums.slimdevices.com/member.php?userid=11550 View this thread: http://forums.slimdevices.com/showthread.php?t=84903 _______________________________________________ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/mailman/listinfo/audiophiles
