In your case I would be going for the HE-500 or LCD2. The HE-500 has a more forgiving and less strident treble with similar to better detail and imaging. Fuller midrange and a slightly laid back sound. The LCD2 is basically what you should upgrade to if you are enamored with the HD650 fully...

I also use the HD800's for my movie watching and PC gaming. The ambient noise, backgrounds, detail in busy scenes and all that make it a much more lifelike experience.   I think something like the DT880/AKG Q701 would be a good lower cost alternative for detail lovers in movie watching.  ...

I picked one of these up from a fellow headfier. Iroko 5/10.   There are a few similarities between these and the Grado PS*** series headphones. The bass is certainly interesting and bit addicting at least for certain types of heavier rock music. Anyone with these should check out Spirit...

The Mad Dog 100% needs an amp it is no where near as sensitive as the 240 or DT770. Maybe going the Shure 840/940 might be a better idea if you don't want to grab an amp as well. Shures though seem to have poor THD ratings on some of their models, which might be the distortion you are hearing...

My Favorite album for the year is Deafheaven: Sunbather         My favorite song is a weird one but a goody *for me at least*   Vicarious Redemption by Cult of Luna  

  Of course, I'm just saying it as something the OP should consider as well. I don't think he has heard any of the cans mentioned at all so it is impossible to know what his preferences for treble are at all.

Grado's just have that pure energy and that fat aggressive guitar + bass tone not nailed down by other headphones. I do enjoy more "technical" headphones a lot for Rock music as well, but with Grado's you can sit back and be taken away without worrying about the technicalities or if they have...

Grado 225i? Maybe 325i   Sennheiser 25 I II   Both of which are more aggressive in their sonic than many of the aforementioned. Grado's really do get the guitar tone down perfectly for that fat rich amped sound. The Senn's are bloody quick and aggressive for metal music.   V Moda M100's...

Wish I could have got a Bushmill's Grado before they sold out.   You should love the RS1's, they are a more refined and classy beast than the SR325, but still with plenty of energy. There are diminishing returns, but I'd be surprised if you didn't notice improvements at least in clarity...

*$1590 for the HD800's  - At Addicted to Audio and Headphonic.   $2099 for the AKG K812 ~ Marked from an original $2599 pricing I believe. At A2A, and also quoted on as $2599 on Headphonics forum.      

I mainly listen to Trance, House, Big Beat, Chillstep, Dubstep and pop genres on the TH900's of mine. I appreciate the slightly more open sound of the TH900 over the 600's. It was a no brainer to buy the TH900 for that extra 15% clarity, openness, smoother treble and slightly more impacting bass...

Just be aware that the Beyerdynamic T90 has a fair bit more treble than even the T1, too much for some peoples ears.

  Depends on the rock I'd assume. For more aggressive Rock music I've seen people swear by the HE-6 as one of the best there is.   In the shoes of someone going for 2 top end models I'd be going HD800 + Fostex TH900 for sheer variation and big differences between the sound signatures.

Portable use go with the Momentum.   At home the Mad Dog 3.2 smokes the Momentum in overall sound quality IMO. Better imaging, detail, I prefer their slightly better extended highs, deeper bass extension and I far prefer the mid range.

Like I said earlier, the Beyerdynamic T1 is very much top end and sounds very very good with all genres. Especially acoustic as well. It is expansive in the soundstage and imaging is very good for gaming. It could easily do both things comfortably.   In pure high fidelity it smokes the Grado...