Just wanted to say that I feel fortunate to have picked up an HPA-9 while it was still in production. It’s really made my main stereo rig come alive, and the headphone amp section is just flat out awesome. Sorry the market wasn’t there.
To anyone looking for a headphone amp that can double as a pre, see if you can find one of these used.
Finally, someone asked whether the gain switch affects the RCA output. Based on my observation, no, just the headphone outs.
The demand for pure preamp/headphone amp is just too low to justify making another such product in the foreseeable future.
Our design engineer is probably "heart broken" as HPA-9 is a great achievement, especially at this price. Perhaps we should have double the price and sales would be better (no kidding).
Head-fi.org has some good user reviews of HPA-9.