beyerdynamic dt-770 vs 990

Most of the 5" low-mid driver speakers have some sort of bass boost either worked into the ported design or via active circuitry ala those insanely shite, tiny Genelec models.

The Yamaha HS80ms are the best monitors I've heard in that price range. They definitely give the KRK RP series a run for it.

Still they're shite in their own way. Low-end is flabby, midrange is unclear and the tops don't seem all that crazy awesome to me either. The ported design is a trade-off from low-end clarity to extension and the 8" woofer is a trade-off from midrange clarity for more extension. Gotta work out what is most important to you, as speakers in that price range don't do it all. They usually do one thing alright, or all things average to downright shite.
 
I just received my DT-990 PRO yesterday actually :) Burning them in with music right now... still have about 60 hours to go :S

I tried them on real quick and wow... they felt like silk against my ears/head. I'm sure the sound won't be any worse either, so it should be a pair of really good headphones.