Presonus HP2

I've had this headphone amp for a few months now, and I can say it's ok, and even very decent for it's low price. The gain on the headphone amp is clean, and there's enough of it. Battery life is pretty decent, but sometimes less than the advertised 7 hours, especially when working in colder environments.

The pots feel slick but with enough resistance that they stay in place.

there are a few drawbacks though, mostly from a design area:
- you need to make sure you have a coin, knife or screwdriver of some sort if you want to change battery, just to open the belt clip (which you need to remove before you can swap the battery).
- the battery compartment itself is a bit clumsly, you kind of need to fit the battery in the lid before closing it, and it can take you a few tries before everything fits. It's also doesn't close that well, and you pretty much need the belt clip over it to make sure it doesn't open. The cable management for the 9V battery also is flilmsy and ill suited to its task, and I worry that it might break over time.

But my biggest gripe with it is the on/of switch. It is a rather large button on the bottom of the device, and can be jostled easily when working on it, especially when working with it live, or during recording jobs (like with a boom op or stuff like that). So it's prone to suddenly shut off. Presonus should really replace it with a sliding switch of some kind so that it much more secure, especially since this is intended as a mobile device to be worn on the body.

If you're on a budget and want a mobile battery powered headphone amp, this is a pretty good option though. just be carefull with the power button.