I finally tried the LCD3s with my RSA B52 and really liked the combination.
The B52 likes a headphone with a solid bass, and that's exactly what the LCD3 has. It creates a very balanced sound that is refined and has good detail.
It is not a sharp or pushy sound, but the resolution is very good but you don't feel like anything is in-your-face, even with brash CDs. In fact, this is a great combination for lesser quality recordings, like 80's CDs that can be sharp or full of glare and have excessive bite. There is great density and saturation of vocals and mids.
I do NOT feel like things are hidden or suppressed, just handled with elegance. The LCD3s are the best phones I ever heard out of the B52 (after many others like T1s, PS1000s, D7000s, bass-light R10s, K701s).
The HD800s are also very very nice from the B52, but the LCD3s here are more fluid and compelling, and can be played at higher volumes.
The B52/LCD3 is great on some piercing female vocals (Diana Ross, Mama Cass, and others) , which could make me wince at times but are smooth but not smoothed over in mid-fi style, if you know what I mean.
I'm writing this because, as far as I can see, I have never come across the B52 / LCD3 combo mentioned in the forums, after all these posts (and I can't recall any LCD2 Rev 2 /B52 mentioned either).