There was a thread a while back asking about headphone amps designed for bass. I was in the process of purchasing a Cafe Walter at the time, and was asked to provide a review after I had some playing time put in. I've put in a few hours of playing time with the unit, and am very pleased. It's a funky looking unit... very 'boutique' looking... with a simple steel case. Very sparse, with volume controls for 1/4" instrument input and for an auxiliary input (stereo mini plug input for MP3 player, etc.). It also has an auxilary output and an AC adaptor (included in the price). A red power light comes on when you plug in the instrument when using battery power. The unit stays on when using the AC adaptor. I'm using Bose Tri Port headphones with the unit. The headphone output is stereo, so no need for any sort of stereo to mono adaptor. The unit is very transparent and has plenty of input headroom (which I found lacking on most other units), and tons of output volume. Even aggressive slapping and hard finger style playing on the B string did not overdrive the input stage of the unit. Very nice! I played a number of different basses through the unit, and it did a good job of reproducing the inherent voice of each instrument... from the growly, raspy, aggressive grind of the 70's J Bass-oriented Celinder Update 5 to the big, mellow, organic fat lows, warm mids and 'hi fi' treble of a Jerzy Drozd Excellency with an OB-3 pre. All in all, a very high quality, usable, well built unit that is great to practice through. Very highly recommended. Bass Northwest has them in stock.