There are several other things you can do to help out: vibration control, change out the fuses, power chords, ICs and of course the USB cable. Just my 10 cents!
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:
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.
I had my DAC-1 modified by Chris Johnson (of Conrad-Johnson fame), in which the mod focused on the RCA outputs. Frankly, it's because I have Kimber Select 1036 interconnects that I didn't feel like replacing with 1136's. So it's Locus Design Cynosure USB into the Benchmark, 1036's out to powered Mackie speakers...also meant for pro audio, FWIW.
Thanks to everybody's input to my thread, Regarding vibration control, having spikes underneath might help but I can live with the stock rubber feet. Adding weight on top makes the sound dull and less alive. Unless you have a bright system, the DAC-1 is meant to be a free standing item without weight on top of it. I know this is surprising because common sense tells us light-weight components benefit from weights on top.
I've tried many things including MapleShade heavy hat/foot, vibrapods, various wooden feet, various metal cones, Totem beaks etc. Finally I just let the DAC-1 sit on a 2 inch solid maple board with its original feet.
I had the Chris Johnson mod and just had the opamps of that mod changed by Chris to the Burson discreet op amps. Chris said the change would be "massive" and he was right. All the hardness that was sometimes evident with the DAC and not very good recordings is gone. The sound is more detailed but much, much more natural. I still have the balanced outs with the original chris johnson mod and when I switched from the rca outs with the Bursons to the balanced mod without them, I felt as though I had gone to a shrill sounding low-fi system.
Fine comments, all of which highlight the excellent quality of the DAC1 and, because of its quality, how well it responds to changes and upgrades.
A few more things.
(1) Digital interconnect. Extremely important for the DAC1, or for any dac, is the digital interconnect (if you're not using USB). I found that using the Stereovox XV or especially the Stereolab XV Ultra made a big big difference.
(2) Transport - If you're using a transport, don't follow the idea that the transport doesn't matter because of the DAC1's jitter elimination features. If you're using a cheap DVD player of low-mid CD player as a transport, you're missing plenty. Try a high end transport and you'll be amazed.
(3) Other - As mentioned above, a fine powercord like the Shunyata Python and power conditioner like a Shunyata Hydra make big improvements. A HiFi tuning fuse made a nice improvement.
I use the balanced outs to a Pass X150.5 amp and it sounds superb. Of course, fine interconnects from the DAC1 help greatly too.
Believe or not digital cables do make a difference, and sometimes bigger differences than the transports. You don't have to spend a lot, but organic-sounding digital cables work better with DAC-1. Benchmark's own AES/EBU is cheap and good, and better than Benchmark's RCA/BNC cable, but it's not forgiving, just like the DAC-1 itself.
Kijanki, call Benchmark for the location of jumpers, I have the DAC-1 USB, and every model has different versions, so the circuit board layout may slightly differ.
I've found that Herbie's Tenderfeet work wonders for desktop usage. Simply lifting one side of it up by one finger can provide a hint of what this can do for the sound. It's subtle, but significant enough to be worth the modest cost of the feet. It helped eliminate the bloated, forward bass and edgy highs that I was experiencing with my Denon AH-D2000 headphones playing through the headphone jack.
To be fair, I'm using an older base model that came with the rack-mount face plate (revision g, maybe?) directly next to my laptop on a fairly cheap desk, so maybe newer models on better platforms aren't as susceptible to vibration issues. Worth a shot either way.