Headphone Amp for Portable CDP


Since many of the better headphones IE Sennheiser HD 580 + 600 etc have impedance greater than 100 ohms, and most portable CDP have low output level to conserve battery consumption, an inexpensive headphone amp is needed for best sound. What amps are members using for under $400 retail?

Popular models include Creek OBH 11, Musical Fidelity X-Can 2, Grado RA-1 (battery powered) and various models from Headroom etc. I own Sennheiser HD580 cans and would like to run from portable CDP at home, any suggestions or recommendations for amp?
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I use the HeadRoom Little but with a twist. I run the portable CDP first into a TDS Passive Audiophile unit and then into the Little. I recently saw the TDS unit for sale on Audigon for less than 50% retail and if you picked up a used Little, you would be under your $400 limit.
SM I do own a TDS Passive Audiophile now, and could not even
for a second think of removing it from my main system, but
I like your thinking! I am hoping to buy new/used amp for
$300 tops and was wondering how the Creek,MF,and Grado units
compare to Headroom units available for $300?

Any thoughts
The Grado RA-1 fits nicely into your price range and is excellent at driving Sens. Headroom will let you buy two amps and then return the one that comes in second during your audition. X-CAN is also good, and is superior to Creek at least with my gear, but I think the Grado is the best under $1K.