@Russian1
The Fostex TH600 are pretty amazing cans, especially if you can find them for $600 or below. You can get more sub-bass punch without EQ from them than most other headphones I've used, and I've heard many. They've just been discontinued, so they're becoming both harder to find and sometimes less expensive as places clear out their inventory.
Of all the basshead headphones that I've heard--and I've heard everything on the Top 10 List except the Yamaha Pro 500 and Sony XB1000 (and many that aren't quite on the list)--the Fostex TH900 are the best sounding basshead headphones without EQ, followed almost imperceptibly for me by the TH600.
The negatives of the Fostex TH600 are as follows: No detachable cable, the highs can get a little fatiguing (but are calming down as I use them more--must be burn-in taming them), some people have had problems with the screw that attaches the earpieces to the headband getting loose, and they don't isolate as much as a truly closed can.
I also have the AudioQuest Nighthawks on my ears right now. Compared to the TH600, these are less bright in the highs, have slightly less bass impact, are a little more comfortable, and do have detachable cables. They isolate roughly the same amount as the Fostex; I'm not really bothered by others at work--nor are they bothered by me--with either headphone.
The Fostex TH600 have a bit more bass impact than the AudioQuest Nighthawk both with and without EQ and are a bit more fun to listen to, but the Nighthawks really can be listened to for many hours without fatigue. Neither headphone is completely broken in. The Nighthawk are supposed to be broken in for 150 hours (according to AQ), and the Fostex are reported to continue burning in for about the same amount of time. I probably have 20 hours on the Nighthawk and 60 hours on the TH600.
I have listened to them back-to-back, but never in extremely rapid succession. To do that, I need both at home since I can output both simultaneously from one source. I'll do that next week sometime since the in-laws are in town and are staying in my office where I can actually listen to them both.
My next favorite basshead sound signature without EQ would be the V-Moda Crossfade M100 with the XL pads. They have better isolation than the Fostex or AudioQuest cans and are actually portable. Their build quality is also top notch. I thought they sounded great and would have kept them, but I have stupidly tall ears and even the XL pads didn't quite go all the way around my ears. If you have a Best Buy near you, you can probably try them out without the XL pads. They aren't quite on the same level as the higher-priced cans, though.
I have never heard any Ultrasone or Audeze headphones, and both have basshead-worthy contenders according to others that don't quite make the list.