[dbdynsty25]

I had the M50s for a while and ultimately returned them for the HD25s.  There are two reasons.  One, I wasn't a fan of the "over the ear" design, I wanted ON EAR closed backs and two is that the mids really were recessed on the M50s.  The HD-25s just seem to sound better as a whole without sacrificing the nice bass response that you get on the M50s.  In fact, it isn't quite as boomy, but it is definitely plentiful.  I listen to mostly rap and some rock and the HD25s are perfect for this.  
 
The downside is that they cost $100 more...but the increased performance and the preferred on ear design won me over in the end.

 

[SillyHoney]

Quote:

The downside is that they cost $100 more...but the increased performance and the preferred on ear design won me over in the end.

That $100 more makes it a very different story lol

 

[jr41]

The Sennheiser HD 25-1 II are excellent headphone for portable use, I'm really pleased with mine. Great sound (detail, nice, well controlled bass and dynamic sound) and isolation. They're also very rugged. The only disadvantage is their look is perhaps a little, well, industrial(?) for some tastes.

 

[miloxo]

x 3?  on the HD25's
 
Small, very lightweight, good isolation, good sound and build like a aircraft carrier. 
 

 

[TobaccoRoad]

To be honest I never thought HD25 would be so popular for portable use. Who the hell wants to look like Marv Albert commentating in public?