Best $200-$300 Headphones for a Very Large Head

I'm interested in getting a new pair of headphones, but I'm having a hard time finding comfortable ones that are the right size.  My head is quite large, so the largest hat size that I've seen (8 1/8, or 25.5 inches) doesn't fit my head.  Therefore, I've had a very tough time finding headphones big enough to still be comfortable.  I currently have a pair of JVC noise cancelling headphones, but I'm finding that they get uncomfortable after about an hour of wearing them.  My budget is $200-$300, and I'm interested in having better sound quality than the JVC but still be comfortable.  The JVC headphones are ones that go on the ear, so they end up squishing my ears and making them hurt after extended use.  I haven't tried any headphones that go around the ear instead of on the ear, so if those are more comfortable, please let me know.  Finally, I mostly use my headphones on the computer and I currently have them plugged into the on-board motherboard sound system.  I've read that it is better to have an amp to make the sound quality better, so should I also get something like a sound card?

Thanks for any suggestions you have!

I've actually tried the Audio Technica AD900 headphones before, but I wasn't too happy with their comfort.  Since the ear cups (sorry if this isn't the right word for it) can't rotate, all of the clamping forces goes to the bottom part of the padding, making them rather uncomfortable for me.  The Denon D2000 look like they would work better since they seem to be just as large but can rotate, so I'm going to see if the music store close to me has any of those to try out.  The Asus Xonar DG soundcard looks like a great solution for the price, so I will probably go with that as my soundcard.

For the type of sound that I like, I'm not quite sure.  I listen to a lot of different audio, from video games like Battlefield 3 (lots of bass in that game) to music that has a lots of little details from many different instruments, so detail oriented work best for that.  I'm not sure what the different types of sounds are like since I have only recently began caring about audio (which is why I bought my JVC's), so I would say that headphones that are good with lots of different kinds of sounds would be best for me.  Hopefully that is enough information for you to understand my situation, and thanks for all of the suggestions so far!