From what I can remember using the Lyr -> MDs/HE-500s/LCD-2s
The soundstage of the HE500s vs the MD's was bigger (obviously), IMO the HE500s are way way brighter than the Mad Dogs and the LCD-2's. When I bought the HE-500s I would looking for a slightly slightly teeny weeny bit brighter LCD-2 sound. The sound of the MD's in my opinion is much more smooth and the precision is just so tight and on point when compare to the HE500s. I had the LCD-2's first then the MD's then the HE-500s so when I say that the HE-500s seemed more sterile than the LCD-2's/MD's that may be because I was going from the LCD-2's but the HE500s just seemed sterile and like an ortho DT880s. I still enjoyed the HE500s but couldn't imagine using them without tubes, I just think that they would seem even more sterile and dry.
The MD's on the other hands and in summary were just very smooth and the precision and control of the bass is excellent, they were also never too bright.