Benchmark 1, 2 & 3

I was very surprised to see that. There is a significant difference between the DAC1 and DAC2, as most reviewers said at the time of the DAC2's introduction -- more detail, smoother, less bright -- overall much more listenable. I had the DAC1 and DAC2 at the same time (before I sold the DAC1) and the improvement with the DAC2 was apparent to everyone who heard it in my system. Frankly I wouldn't touch a DAC1 at this time - only get a DAC2. 

I can't comment on the DAC2 v. the DAC3 -- I haven't heard the latter -- but Benchmark itself has stated there is no audible difference (which is a bit hard to believe given the change in dac chips.)  Personally I'd get a DAC2 and pocket the difference.

Compare the Stereophile measurements.

I would echo @dne statements, I have owned all 3. I could not tell a difference between 2 and 3. From 1 to 2 was a massive improvement for me. Allowed me to go direct to amp and sell a preamp. I think a preamp is still better but I needed the cash at the time and the 2 came to the rescue.