Benchmark DAC1 ($995)
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Peter_s, there are two other iPod docks that can get the digital iPod signal - one from Denon and one from Onkyo. The Onkyo has a nicer look. Peachtree should come out with their iDecco in Jan - an integrated with a digital iPod dock and Sabre DAC built in.
I expect more manufacturers to enter this game in 2010.
Pkubica, I was referring to the Onkyo ND-S1, see review here:
I cannot find this dock anywhere but on websites in the United Kingdom. It is not listed on Onkyo's webiste. But it apparently exists if people have reviewed it, I wish I could find it in the U.S.
Funny you mentioned music hall 25.2. I was just reading about one being modded in this blog. It seems to be a popular choice for DIYers which means the music hall 25.2 has some hidden potentials.
Does these DACs really "re-clock". I was under the impression they were jitter immune/rejecting but do not truly reclock.
You are correct in that the majority do not "re-clock", however, the Benchmark DAC is truly "asynchronous" - so it is completely ignoring the input clock and unlike most other designs it is not trying to keep in time with the input clock.
i have confirmation from PS audio tech support that their digital link III does re-clock the incoming signal. Documentation for the Music Hall 25.2 DAC specifically claims it re-clocks the signal. I am not sure what "asynchronous" means - if the Benchmark ignores the input clock, it has to apply some kind of clocking to the signal before it sends it out to the pre amp, right? Can we say then that it "re-clocks?"
You can read about Benchmark's technology here: http://www.soundonsound.com/sos/jul05/articles/benchmark.htm
As far as I remember at 50GHz most of samples are redundant. This frequency is not real (1 million times oversampling) and is based on statistical manipulations(finding exact spot for the output sample).
They also mention updating output DAC at only 110kHz. Most of DAC chips have higher THD at 192kHz than 110kHz.
Asynchronous upsampling never brings exact oversampling ratios. If specification says 4x,8x,128x etc. then it is not asynchronous upsampling converter but rather oversampling one based on PLL (phase lock loop).
Kijanki, all tech speak aside, i think we all agree that Benchmark's product probably sounds better than the music hall and the ps audio. You are saying Benchmark has less distortion, your post is in favor of their product? I am a bit more new to this research so could you expand a bit on what you are saying? thanks.
Realremo - Benchmark is not on the warm side. It is pretty neutral and resolving/revealing. I have class D amp (Rowland 102) that is also neutral and resolving. Combination of two with my previous Paradigm Studio/60 v2 speakers was a little bright (painful on some records). I changed speakers to Hyperion HPS-938 and now everything is creamy smooth and even bright recordings sound nice and musical.
Before Benchmark I had Cambridge CD4SE. I was really surprised with Benchmarks clarity. Initially it sounded like some instruments were missing (too clean). Some people call it sterile - I call it very clean.
I cannot tell you how it compares to other DACs since I never had other DACs in my setup.
I am surprised that no one has mentioned the MF V-DAC - I guess it does not re-clock the signal. It gets very high scores on comparison tests with other DACs that are much more expensive.
Per the Empirical Audio website, once jitter is removed or greatly eliminated, the playing field is leveled for DACs, so maybe my path is MF V-DAC and Airport Express for now, then purhcase a re-clocker later (like the Pace Car). I would like to run PC Audio wirelessly using digital coax, does anyone know how? Nugent thinks optical ICs are more jitter-prone than digital coax.
Realremo - Airport Express has only optical out but it doesn't matter if DAC has very strong jitter rejection. My Benchmark has jitter bandwidth of few Hz and at frequencies of interest (kHz) has over 100dB rejection (of a jitter that was -60dB or lower). Stereophile wrote primer on jitter http://www.stereophile.com/reference/1093jitter/ You'll find some info on reclockers there.
Jitter is noise in time domain. In frequency domain it creates sidebands that are not harmonically related to root frequency and therefore audible even at very low levels. With music (complex signal) it is basically noise. Since it appears only when signal is present and it is proportional to signal level it cannot be detected without signal and can be judged only as a lack of clarity.
Typical transport's digital out switches with about 25ns transition time. Better transports do it perhaps faster. Faster transition means more problems with reflections on characteristic impedance boundaries but slower transitions suffer from induced noise or threshold/system noise (case of toslink). Whole thing depends on all three components (transport, cable, DAC) but Toslink in general makes about 2x worse jitter than coax. On the other hand if your DAC has strong jitter rejection then Toslink might be a blessing because it breaks ground loops.