Sennheiser HD 650 Headphones

Great headphones. Try one of the aftermarket Zu Mobius cables and they get even better. Also the tube headphone amps from Singlepower are very good with the HD650.

Another growing site to check out that seems alot more geared towards the higher end headphone listening is.
www.head-case.org
It and head-fi.org will get you any info on headamps and phones you will need.
i have owned two over the top Singlepower amps in the past(SDS and SDS-XLR) and now have a Singlepower Maestro-XLR with outboard tubed power supply that pulls preamp and headphone duty. Amps like these and others take the Senns to a whole new level of headphone listening.

Sometimes they are a little tough to pull off. grabing them by the connector (not the cable) with needle nose pliers or something along those lines will work. Ive had some pr. that you really have to work to get them loose the first time. Just pull straight out very hard and they will come loose. Try not to wiggle them back and forth. Just pull straight out. You can find the cables used sometimes in the cables for sale forum on www.head-fi.org. But your best bet is go right to www.zucable.com and order a pr.