After trying out JDS Lab's cMoyBB Headphone amp, I was in awe about what a simple headphone amp could do to a great pair of headphones. Thankfully, there are several cheap options available. PenguinAmp, located in Germany, is run by Robert Gehrke. They also manufacture headphone amps in mint tins. I tried out the Caffeine amp for a few weeks and was pleasantly surprised.
Instead of a custom circuit board that is exposed when open, this amp is flipped and you can only see the deep black board that is used. It has some good components though: an AD8397 opamp and a large capacitor along with the other components necessary to create a virtual ground and make high quality amplification. Similar to the cMoyBB, a bass boost is offered.
While not a true cMoy because of the slightly different setup, this amp sounds wonderful. Its sound quality is similar to that of that made by JDS Labs, but the bass output seems a little clearer with boost enabled. The downside however, is that there is an on/off switch instead of auto-sensing. Battery consumption was slighty shorter than the cMoyBB. Still, the interior is cleaner and the 9V battery plugs directly into the board rather than via a set of leads and connector. The components sticking through the mint tin look much cleaner because of high quality holes which are more precisely sized. Still, there is no self-build kit so DIY-ers aren't able to build themselves.
While I love both amps, which one to get depends on what you like more: the Caffeine will get you a cleaner designed amp, but the cMoyBB is the only one you can build yourself. Both drove a pair of Sennheiser HD650s well, so it comes down to what you want more. The only serious draw back is the lcak of auto-on sensing to decrease accidental power consumption.
PenguinAmp Caffeine – 9/10
[PenguinAmp Caffeine] – $69 w/ $7.50 shipping