Pros: Well priced, neutral sounding
Cons: 9V battery, average/small soundstage, no limiter for voltage input
I've had the privilege of Charles Wong send me this prototype amp a few months back but didn't get a chance to listen to it until recently. Charles worked on this particular unit himself so it is still very much a prototype unit that I have in my hands. There were a few issues with the unit but since it's prototype, I won't dwell on that.
Overall, the unit is quite blocky due to the 9V battery it houses and the wooden case does have some thickness to it. The actual circuit board inside is actually quite small. Operation is quite simple, only a volume pot that acts as a off/on switch too. No gain switch option either. I did encounter an issue that any source with a "high voltage out" seems to introduce distortion in the amp. Therefore sources such as the HM-901 line out is too powerful for this amp. However other DAP/DACs (AK120, VentureCraft DD) I've tried seem to be fine.
The sound of the amp is actually neutral with a slight treble bias. It's actually quite a reasonable amp to use if one wants to "cleanse their sonic palate" in preparation for critical listening of other amps. The soundstage is somewhat smaller than what I'm used to but at the same time I don't really hear congestion. It's price of $200, it's actually reasonable for what it delivers.