Al - Benchmark had all sorts of problems so be careful with used one (and the new one has 5 years warranty for original owner). First problem in very early Benchmarks was thin sounding NE5532 made by Signetics (Philips). Fortunately Philips factory burned down around 2001 and license was bought by TI. Die was redesigned (larger) and the sound got fuller. NE5532 is very fine sounding opamp in spite of the price (but horrible DC spects). Second problem was too high impedance on unbalanced outputs (many people preferred to use headphone output for that) and the final minor problem (that my Benchmark suffers) is a little high balanced output impedance. The worst one is at -10dB settings that is perfect with my amp and speakers. I'm forced to use 0dB position (narrower adjustment range).
USB version has different Opamp (but only for the output stage) - newest and greatest LM4562. National got awards for this amp but mostly for combination of great AC and DC spects in one amp. LM4562 is a stronger amp and output divider was redesigned (reduced impedance). Oh there was also something about limitation to 96kHz at optical. It was changed to 192kHz with rev F. (same rev. F reduced unbalanced impedance to 30 Ohm). Benchmark has 30 day free evaluation program.
Word of a warning - Benchmark is not a warm sounding DAC. According to John Siau it was meant to be neutral because warm sound (exaggerated even harmonics) sounds wonderful with voice or guitar but not with instruments that have more complex harmonic structure than simple overtones (like piano or percussion instruments). He even mentioned that piano might sound like out of tune with some very warm systems. I don't have much of experience in audio and therefore believe in what I read.
There are mods for DAC1. One of them is to change cheap amps to OPA627. Benchmark tried them and they prefer NE5532. They even show which harmonics got worse. Steve from Empirical Audio says that microdynamics (low level performance) is improved with OPA627. Steve also improves power supply - filtering and decoupling. In spite of -140dB measured S/N of the stock units Steve says that dynamic performance is improved (pulse response). One thing not acceptable to me in mods is removal of upsampling scheme. I don't question that it sounds fine but requires high quality transport a not my $60 DVD player.
USB version has different Opamp (but only for the output stage) - newest and greatest LM4562. National got awards for this amp but mostly for combination of great AC and DC spects in one amp. LM4562 is a stronger amp and output divider was redesigned (reduced impedance). Oh there was also something about limitation to 96kHz at optical. It was changed to 192kHz with rev F. (same rev. F reduced unbalanced impedance to 30 Ohm). Benchmark has 30 day free evaluation program.
Word of a warning - Benchmark is not a warm sounding DAC. According to John Siau it was meant to be neutral because warm sound (exaggerated even harmonics) sounds wonderful with voice or guitar but not with instruments that have more complex harmonic structure than simple overtones (like piano or percussion instruments). He even mentioned that piano might sound like out of tune with some very warm systems. I don't have much of experience in audio and therefore believe in what I read.
There are mods for DAC1. One of them is to change cheap amps to OPA627. Benchmark tried them and they prefer NE5532. They even show which harmonics got worse. Steve from Empirical Audio says that microdynamics (low level performance) is improved with OPA627. Steve also improves power supply - filtering and decoupling. In spite of -140dB measured S/N of the stock units Steve says that dynamic performance is improved (pulse response). One thing not acceptable to me in mods is removal of upsampling scheme. I don't question that it sounds fine but requires high quality transport a not my $60 DVD player.
