The HPA v.1.0 is a classic and the first “high end” item I bought as a grad student along with a pair of HD 580 cans. The latter have long since stopped working, but this unit still functions. The fine little amp functions in Class A and sounds very nice. It has obviously been around the block a bit and was languishing in a desk drawer — it has no rubber feet any more. Nice little item at this price for a collector or DIY enthusiast.
No power supply is included, so you’ll need to find a +/-12 V supply that terminates in a 3.5 mm “mono” or TS headphone-style plug. I built my own once-upon-a-time out of two 12V DC supplies.
Included: free US domestic USPS shipping
Not Included: original packaging, manuals, RCA interconnects, power supply