Chayro - Excellent post. I'm not implying that you're implying that Robbob is ignorant though.
Robbob,
I heard a decent amount of difference between the W4S DAC1, Benchmark DAC1 and Rega DAC in my system (Bryston B60 and Audio Physic Yara Evolution Bookshelf).
They're harder to put into exact words though... The Rega just made better sense of the music than the others (and all others I've heard in my system). Music (not just sounds) was easier to follow and subsequently get lost in. My ears were constantly in analyze mode with the Benchmark and W4S (although not nearly as much with the W4S).
If I were to get technical with it, the differences wouldn't be that great. The Benchmark sounded a bit bleached, the W4S sounded yadda yadda yadda. In the technical aspects, their wasn't that much difference. In musical ebb and flow and musical enjoyment, the Rega was far better than anything I've heard at home. Sounds like a cop-out, but it's genuinely not.
Case in point - my wife tolerates my hobby. She doesn't criticize, but she thinks I'm a bit too geeky with this stuff (she's right, btw). I'm not saying even she heard the differences, but in a roundabout way, she did...
When I brought the Rega DAC home, unbeknownst to her, I had it playing a few tunes I love, but she's never cared much for. That was the first time I've seen her foot tap to the music. When I went to turn it off, she asked me to keep it on - another first. She enjoys music in our home more now than ever.
Wierd, huh?
For the record, I didn't sneek the Rega in. She frankly doesn't care what I buy, so long as we've got heat, electricity, food, and our daughter is fed. I just had it set up and running before she got home.