Headphone Amps

I know absolutely nothing about headphone amps. Where do I start? What are the typical models that people begin with? Is there something specific I should be looking for? Is there a recognized standard in headphone amps? The best? The most affordable? The best buy? Thanks all.
I use a tubed headphone amp made by Antique Sound Labs called the MG Head. It is a VERY popular little amp. The company that sells them is Divergent Technologies, www.divertech.com . Also if you would like to find more info headphone equipment in gerneral, visit www.head-fi.org or www.headwize.com .I personally use the ASL MG Head and a pair of Sennheiser HD600's. They're an awesome combination. I hope this info helps. Zach
One of the best online retailers of headphone amps is Headroom, at http://www.headphone.com .

Headphone amps come in all types: SS, tube, cheap, expensive. Common starters include the META47, the aforementioned MG Head (said to be really excellent value for the price, if you like tubes), and the lower end Headroom amps (SS). As with speakers, matching amp to headphone is important, in terms of sound quality and also impedance (not all amps are capable of driving low impedance headphones).

When you are ready to move up to something a little better, consider the EarMax Pro--tube amp, can drive many kinds of phones including most low impedance phones.
I second the Headroom recommendation, after first owning a Cosmic, and now the Maxed Out Home Reference. I have friends that are into tube electronics who boutght and the MOHR, and don't miss anything about it. It is smooth, acurate with solid bass. It is 97% of the MAX. I use mine at work with a CD-3400 and Theata DAC. You won't be sorry and for $1100 the amp is a satisfier. The MAX is nice but bang for the buck is the MOHR with Etymotic ER-4S or Sennheiser HD600's. Happy listening!!!!!!
I preferred the Musical Fidelity X-Cans v.2 to the ASL MG Head DT powering the HD600's. There are plenty of archived threads on this topic you should check out for more.
try www.headwize.com...I think that's a headphone specific forum with plenty of info. Search the archives here and at AudioAsylum too...lots of info in both.
The David Berning MicroZOTL is a very nice headphone amp.
i just picked up a Grado RA-1 headpone amp from a fellow audiogoner and haven't really used any others but this sounds very good with my Senn HD-600s. It's a battery powered unit, fairly small, and as such it's portable, which should come in very handy on trips. It's relatively inexpensive used and might be something else to look at. Good Luck, Mike.
Thanks all!!!! Let the research and listening begin!!!!!
Suggest you check out the forums at Headwize.com and head-fi.org for more info. Also highly recommend that you buy nothing w/o a rite of return. I have tried 3 different headphone amps-Audio Alchemy, X-cans and Earmax. Only the Earmax was better than what I usually listen thru (Headphone output of NAD receiver) and it wasn't better enough to justify its cost. After trying those 3, I lost interest in them, decided to upgrade my front end and headphones instead-better ROI.