I've had a Benchmark Media DAC1 for about nine months. I think it's a great product for the price, especially if you're directly connecting it to a power amp, but be aware of some weaknesses. In my system, directly driving a PS Audio HCA-2 with balanced XLR connections, the performance of the DAC1 is highly dependent upon AC power quality, power cords, and power conditioning, etc. Experimenting is strongly suggested -- I still am. Additionally, the performance depends a lot upon the interconnect used, and the internal level settings (I'm using -10 dB setting). I can't comment about the performance of the single-ended RCA outputs. Again, experimentation is strongly advised. Vibration isolation experimentation is also advised -- I'm currently using Black Diamond Racing Cones MK IV, but still experimenting.
As far as variation in performance with various digital sources, such as Ciscomc suggests, I haven't found that to be the case, but then I don't have a high priced drive and cable to try, plus all my digital sources are a long distance from the DAC1, and highly power isolated, and completely ground isolated. Ciscomc's experiences with source dependency could be caused by vibrational connections, rf/em interference, AC power interference, or grounding problems. If you isolate all of these, then Benchmark Media's claimed immunity to source and digital cable might be accurate. I've used a variety of coax and Toslink digital sources and cables with negligible audible differences. This was one of the great selling points for the DAC1 for me, since I have four different digital sources connected to it, and I don't like the added complexity of tweaking digital sources. Perhaps, after I get other system issues taken care of, I'll be experimenting with source and digital cable effects.
Even with the issues I've mentioned, the Benchmark Media DAC1 is a wonderful product worth serious consideration if you're in the market for a DAC. Just don't expect to drop it into your system and get great performance (unless you're lucky). Tweaking was necessary for me -- performance can be stunning when you reach a sweet spot. I'm considering the posibility of doing internal modifications to the output stage, power supply, and adding rfi/emi treatment, to see if the performance can be further improved.
I'd enjoy hearing of others experiences.