Yingtonggao - Benchmark DAC1 had two problems at the very beginning:
- thin sounding Signetics/Philips NE5532 OpAmps
- high output impedance on unbalanced (RCA) out.
Texas Instruments bought NE5532 license, after Philips factory burned down in 2000/2001, redesigned die (making it larger) and produced fuller sounding OpAmp used now in DAC1 (recognizable by TI logo - map of Texas).
Unbalanced output impedance was so high that many users elected to use headphones output instead. It was fixed in one of early revisions. Balanced outputs' impedance is lowest at 0dB but -10dB is worse than -20dB. Newer DAC1 PRE or DAC1 USB use stronger output amp (LM4562) and lower impedance divider.
My DAC1 is rev. G and is free from mentioned problems. I use it as a preamp with balanced outputs set to 0dB (I don't have any analog sources). It places volume control in the signal path but according to Benchmark this path is identical (doubled) with or without volume control. The only issue I can see is small inexpensive volume potentiometer but in return I gain some quality (and money) by using only one set of ICs.
This tiny pot. tracks very well (even close to 0) but develops static over time (dust) that goes away after turning pot few times - coming back again next day. Solution to this problem is to lift one corner of the pot's back cover with fingernail or needle (just a needle thickness to avoid breaking) and spray contact cleaner inside (a lot) - then rotate pot few times. I used one designed for fader lubrication:
http://www.amazon.com/CAIG-DeoxIT-FaderLube-Lubricant-oz/dp/B000H2G5R8/ref=sr_1_1?ie=UTF8&s=musical-instruments&qid=1292544268&sr=8-1
You're right about unforgiving nature of DAC1. Benchmark technical director John Siau said once that Benchmark was designed not to sound warm but rather "natural". I had it with unforgiving/revealing class D amp and Paradigm Studio/60 speakers with revealing tweeter. It was very transparent but unpleasant with a lot of unnatural sibilants (energy in 8-11kHz range). I replaced speakers with warm sounding Hyperion HPS-938 and now it is really nice and musical. Sibilants are still there quite strong but very clean and natural. New speakers have soft dome tweeters vs. aluminum dome on Paradigms but are also in different class/price range.
- thin sounding Signetics/Philips NE5532 OpAmps
- high output impedance on unbalanced (RCA) out.
Texas Instruments bought NE5532 license, after Philips factory burned down in 2000/2001, redesigned die (making it larger) and produced fuller sounding OpAmp used now in DAC1 (recognizable by TI logo - map of Texas).
Unbalanced output impedance was so high that many users elected to use headphones output instead. It was fixed in one of early revisions. Balanced outputs' impedance is lowest at 0dB but -10dB is worse than -20dB. Newer DAC1 PRE or DAC1 USB use stronger output amp (LM4562) and lower impedance divider.
My DAC1 is rev. G and is free from mentioned problems. I use it as a preamp with balanced outputs set to 0dB (I don't have any analog sources). It places volume control in the signal path but according to Benchmark this path is identical (doubled) with or without volume control. The only issue I can see is small inexpensive volume potentiometer but in return I gain some quality (and money) by using only one set of ICs.
This tiny pot. tracks very well (even close to 0) but develops static over time (dust) that goes away after turning pot few times - coming back again next day. Solution to this problem is to lift one corner of the pot's back cover with fingernail or needle (just a needle thickness to avoid breaking) and spray contact cleaner inside (a lot) - then rotate pot few times. I used one designed for fader lubrication:
http://www.amazon.com/CAIG-DeoxIT-FaderLube-Lubricant-oz/dp/B000H2G5R8/ref=sr_1_1?ie=UTF8&s=musical-instruments&qid=1292544268&sr=8-1
You're right about unforgiving nature of DAC1. Benchmark technical director John Siau said once that Benchmark was designed not to sound warm but rather "natural". I had it with unforgiving/revealing class D amp and Paradigm Studio/60 speakers with revealing tweeter. It was very transparent but unpleasant with a lot of unnatural sibilants (energy in 8-11kHz range). I replaced speakers with warm sounding Hyperion HPS-938 and now it is really nice and musical. Sibilants are still there quite strong but very clean and natural. New speakers have soft dome tweeters vs. aluminum dome on Paradigms but are also in different class/price range.