Other than the lack of a power switch, I believe that I'll be satisfied with the PM50s for a long, long time. It'll make it much easier to adjust my headphones during shows without having to talk to the sound guy.

Sound
First of all, let me say that I am using this box slightly differently than it was intended. I am using a TRS-TRS cable to connect the headphone output from my keyboard to the PM350s's monitor input, and am sending a generic aux feed from my mixer to the PM350s's mic input, in order to daisy-chain several of these boxes together. So basically, it mixes my keyboard with everything else (a "more me" box). I wasn't sure if connecting 3 boxes in this way would degrade the quality of the aux signal, but when I tested it, it does not. There is no noticeable loss in signal quality at all. The box doesn't alter the sound from either input in any way; it simply provides amplification. Just be careful with the mic input- it is a MIC input after all, so line-level signals need to be very low to prevent distortion. But with the volume of the mic input turned only a quarter of the way up, the volume is loud and clear. I can't think of a time where there ever wouldn't be enough volume with this box, and the last box in the chain sounds exactly the same as the first box: crystal clear.

Features
The box comes with a wall-wart power adapter, and can also be powered by a Rolls PS16 through the monitor input. The only things I would… read more change: I wish the box didn't send a thump through the headphone output when it powers on, and I wish Rolls would have added a power switch. It's sometimes an inconvenience to have to unplug the box whenever I'm done using it. Other than that, it has all the features you really need: two inputs, a mic thru jack, ground lift on the mic jack, and a jumper to set the monitor input as mono or stereo. The mic input knob is smooth all the way from min to max, but the monitor knob has a "stopping point" at the 12:00 position, so you know when the monitor level is at unity gain.

Ease of Use
It literally takes you two minutes to get this set up: plug in your mic, plug in your monitor input, plug in your headphones and the power adapter, and turn the two knobs to adjust the volumes. Easy to learn, easy to use, just like musicians want.

Quality
Other than the plastic/rubber-ish feeling knobs, which feel very professional and secure, the box is made entirely of metal, so I know it'll be protected if it takes a fall off a music stand.

Value
Cheap, 2-channel headphone amp that can be daisy-chained to other units. It's solid, and I'm confident I won't need to buy a replacement for a long time.

Manufacturer Support
Haven't had to deal with support. All 3 monitor amps worked perfectly and identically right out of the box.

The Wow Factor
It's cute and little! Plus it's black, so it blends in with most audio equipment. It looks so...right, sitting there on my keyboard.

Musical Background:
Recording Engineer, Keyboardist, Performer read less