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.
tbadder
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.
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.