Hi Zodiac154!
I can't compare it to any of the other systems that you list, but for what it's worth, my current headphone system is the MG Head DT OTL with the Sennheiser 600. The combo sounds great in my honest opinion.
If you are looking for some things to read that will help you make sense of homebrewing your own amps,
1. If you're still learning schematic reading and good construction techniques try:
http://www.tpub.com/neets/ There's a lot more than that at this site though, so it's worth a look regardless.
2. If you're looking for schematics for a project, try:
http://headwize.com/projects/index.htm
3. If you're thinking about getting into valves ("tubes") go to:
http://duncanamps.com/tdslpe/ It's called the Tube Data Sheet Locator Personal Edition, and it's a freeware programme that will help you track down info on various valves (pinouts, heater voltages and currents, etc).
4. For a technical discussion of how a valve amp works go to:
http://www.audioxpress.com/resource/audioclass/ for a set of PDF files that will tell you a LOT about how power supplies and amps are designed.
5. If you do not have much experience with DIY electronics, I'd suggest the Chu Moy amp as a worthy first effort:
http://headwize.com/projects/cmoy2_prj.htm You should be able to build it for less than $50. It would also give you a chance to experiment with crossfeed circuits and parts upgrades on the cheap. Moreover, there are no dangerous high voltages in the unit (though any power supply cap can still bite you, if given a chance).
Until you feel that you can safely work with the high voltages that you are going to encounter in homebrew valve equipment, I would advise that you stick to opamps and MOSFETs. No offence intended!
Good luck and
Enjoy Your Music!
Morse