Ray Samuels makes excellent headphone amps and his portables are great. However, for portable use, I use an 80GB i-Pod with Apple lossless and Etymotic ER-4P in ear earphones and no portable amp. This gives me great sound and great portability. I have owned 2 very good portable amps that I used with an i-River H140 MP3 player and I must say that it was a pain to have to carry a portable amp around. If you still want to get a portable amp, the Hornet is a good way to go. If you use an i-Pod and a portable amp, the best way to connect them is to use a line dock out adapter with a mini plug because it bypasses the i-Pod internal amp. A home amp rather than portable amp will give you the best sound with your 650's. For portable sources, an 80GB or 30GB i-Pod is a great and very user friendly way to go.
New to headphones - what amp, source?
I just purchased some headphones (Sennheiser HD650) and I haven't had headphones for over 25 years, since back when you could jack them directly into your receiver. If I want a relatively portable set up, I could use an amp like the Ray Samuels Hornet (other suggestions?), but what are folks using for their source that isn't too big? Do most use a full sized CD player, or are there portables with rca outs? I am not really sure how to set this up, so any help would be appreciated.