I wanted to add a few comments as another pleased (amazed) owner of a BDA-1. I have had it about a week, but knew from the first few minutes that it was a keeper. My previous DAC was a Lavry DA10, which is a very musical DAC and has bested Benchmark DAC1 and other DACs in its ~$1000 price range in several reviews I've seen. It was certainly a big step up in sound quality from what I had before, analog out from an M-Audio Audiophile 192 soundcard. But in comparison to the BDA-1, the DA10 sounded muddied. Perhaps my system (Magnepan speakers, Classe amps) needs a very transparent DAC like the BDA-1 to avoid this. All the faults in my system I had previously attributed to the speakers or amp, believing the opinion that a DAC is of relatively low importance and will not have a huge effect on SQ. But now these weaknesses are gone, transients are crisp and everything is more musical. I agree with a previous reviewer that the BDA-1 has "mad PRAT" (pace, rhythm, attack, timing). I especially notice this on jazz horns which previously seemed thin, but rock and other genres also benefit.
After trying the optical and USB out I feel the spdif coax out gives best sound, slightly better than optical and noticeably better than USB. I also leave the upsampling off at to me it reduces the transparency and clarity of the sound (some have commented that it adds a tubey effect). One post said the spdif BNC is superior to spdif coax, but I have not tried BNC yet. USB also has some problems with volume control that I don't have with spdif, I can believe what others have reported that USB out can send high volume surges of sound due to quirks in Windows. Even with spdif, I get slight crackling when the audio playback jumps to a new sampling rate file, which never occurred with the Lavry. It would be nice if the BDA-1 was available with a digital volume control. Since I run the DAC's balanced out directly to my amps, I now must use digital volume attenuation within the playback program (Foobar or Xmplay). I buffer the original 16-bit file to 24-bit, and I believe this means that the program can reduce the volume substantially without altering the 16 significant bits. WASAPI output is available in Foobar and Xmplay on Vista, and to me sounds very noticeably better than ASIO (either ASIO4ALL or with M-Audio drivers). I think the redesigned Vista audio stack has a lot of potential. I use spdif out from the onboard audio chip (Realtek AC889). Realtek has been one of the first good implementations of the new audio protocols in Vista, and using WASAPI, the onboard chip sounds indistinguishable to WASAPI out through a mid-range soundcard like M-Audio Audiophile. I think when Lynx and RME release WaveRT drivers that take advantage of Vista's potential, then the gap between digital out from the motherboard vs. a good soundcard will widen again.
In any case, the BDA-1 has improved my enjoyment of the system by a huge amount and is well worth the increase in cost over the ~$1000 DACs, which is saying something in hi-end audio's world of rapidly diminishing returns with increasing price.
