I was going to post about my experince with the Benchmark HDR, which I sent back and replaced with a W4S DAC-2. But Daverz wrote my post for me already, so I'll paste that:
I also auditioned a Benchmark HDR at home several months ago. Like a lot of people, I found it too lean in the mid-bass, and while the treble was impressivly extended, I found I didn't really like the sounds that were revealed "way up there" (I believe in a live situation that extreme treble frequencies never make it to the ears. I remember a cartoon showing two audiophiles walking out of a concert and agreeing, "Not enough treble!".) I did like the exceptionally clean and bell-like midrange. Also the sound was very immediate and "quick". I really wanted to like it more because it's such a cool piece of gear, but it's not really how I want to hear the music.
Maybe it's an issue of "you can't handle the truth!" Maybe all the other equipment I like is plump in the mid-bass and rolled off on top. Quite possible given that I gravitate towards tube gear.