Headphones-How to Connect?

Thanks to all for the information you have provided me. I have an ARC V-70 amp, ARC LS-15 preamp, Naim 3.5 CD player. Can't listen to it because the children are doing their homework. Looking at the Sennheiser 600 headphones. Do I need a separate headphone amp? If so: which one? If not : how do I conect the headphones to my equipment?

Thanks to all.
Mendota98 - I purchased a Creek OBH-11 headphone amp - there are a lot of hp amps available. The hook-up was from the tape loop out to the input of the Creek. BTW, have the 600s and am very pleased. Haven't auditioned others - yet. Good luck.
Unless your cd player has a headphone jack, you would probably have to run a set of interconnects from the tape out jacks on your preamp to a headphone amp. I am not a big Sennheiser fan (I use Grado RS-2's and Ultrasone HFI-600) but I have heard the Sennheisers sound good with the Earmax tube amp by Audio Advancements. To learn more about amps suggest you check out the forums at headwize.com and head-fi.org. Also headphone.com has a lot of useful info.
Sennheiser are high impedance ear-phones that might not be handled with CD-player or even preamp headphone jack.
In most cases head-phone amplifier is recommended for more pleasure to your ears.
Try to get Earmax or visit www.headphone.com to select an appropriate amp for yourself.
Please note that the amp has to handle 600Ohms load.
Mendota 98: I have the Sennheiser 600's with the upgraded Cardas 10 Ft. cable. I've owned the following headphone amps: Musical Fidelity X-CansV2; Creek OBH-11 AND OBH-11SE, Grado RA-1, Earmax, and Sugden Headmaster. The one I have kept is the Sugden Headmaster, connected to my preamp with Cardas Neutral Reference interconnects. We all have our preferences of course, but I found the Sugden to outperform the others by a fairly wide margin. The Earmax basic version, in my opinion, does a fairly poor job of driving the 600's. If you decide to go Earmax, I'd purchase the Earmax Pro. Good Luck.
I use a pair of Sennheiser 600's with an Antique Sound Labs MG Head OTL amp. The amp really isn't too expensive and they sound surprising good together. Try visiting www.head-fi.org , pretty good site to help you figure out what you may want.