[BrianPeppers]

The DT990 have a lot to offer but I'm realizing more and more that I don't really like this. The culmination of this occurred when I got my hands on some fairly cheap ($200) studio monitor speakers and to my ears they sound much more pleasant than the DT990. The DT990 has great ambiance and bass but the shrill highs lend itself to an overly analytic and somewhat unpleasant sound with most of my music. I listen mostly to dance music - trance, house, music with fast drum patterns and much depth in the mid to high registers. More than that I want to try something different. HD600? HD650? I'm a bit troubled by the fact that they are presumably in the same class as the DT990, but cost more than double. Is the price worth it? I have the Schiit Magni + Modi combo for my DAC and amp, which may be contributing to the DT990's sibilance. 

 

[AnalogSavior]

Give the HD600s a shot.  They are very well balanced, shouldn't have any sibilance, and should work just fine with your Schiit stack.

 

[Head Injury]

Yeah, Sennheiser prices have been pretty high. It's because there's demand for them, though; the HD600 and 650 are very good headphones.
 
The Modi+Magni is neutral, so if the DT990 is sibilant it's because of the headphone. I don't recommend trying to fix a headphone you don't like with colored gear, because that begins a never ending shopping spree and you'll end up with a new amp and DAC for every headphone you buy.
 
Maybe try a free digital equalizer instead. If the DT990 is anything like its DT880 cousin, it has a general treble boost culminating in a big 9 kHz spike. With a 31-band EQ, try lowering the 6.3 and 8 kHz bands until you like the balance, and maybe lower 5 and 10 kHz by half as much to make the transition smooth. With a more common 18-band you'll want to lower the 5, 7, and 10 bands. You can check this graph of the DT880 for reference, or build a graph here. Don't take them as gospel though, every headphone is a little different. And if you can't get it the way you like it, maybe give one of the Sennheisers a spin from a store with a return policy.

 

[MrTechAgent]

Beyer don't mind some OTL treatment.
In my opinion a DT880-600 Ohm with a OTL exceeds the fidelity of my 600s and 650s but that doesn't make them bad...its not that hard to find a used HD600 on classifieds for a decent price.

 

[SunshineReggae]

that have nothing to do with OTL, DT880 just has that kind of sound where it seems in many ways "more hi fi" than HD600 or HD650.
 
Again this obsession with OTL amps. Need understand there is nothing inherent about OTL amp for the sound. OTL only relate to how current/voltage are delivered. Have nothing to do with sound.