This is very simple, flat, transparent, hi-fi headphone amplifier handmade by Walter Harley of Cafe Walter Audio in Seattle, WA. It can be used for any instrument but is designed for bass.
Practicing with this amp helped me clean up my playing a lot. You can’t hide from sloppy playing using this. You’ll hear everything in your tone - the good, the bad, and the ugly. And the good.
Powered by 2 9-volt batteries or AC adapter (included). It has a 3.5mm stereo auxiliary in for an MP3 player or metronome, and a 1/4” auxiliary out for a tuner, mixer, amp, or whatever. I’ll also include the 3.5mm male-male adapter I used to plug in my iPod. Comes in original box.
#283 of 900 made. I bought it new around 2006 or so.
For a lot more info, here’s the link:
http://www.cafewalter.com/ha1/
$130 shipped to US or Canada. If you're elsewhere, let's talk about shipping.
Thanks!
Geoff
San Jose, CA