I picked up an MT-15 today. my second PRS amplifier after the J-MOD100. Firstly - It sounds phenomenal. Pretty much as good as my JP-2C. Seriously. But it is all in vain due to the already infamous humming. I wanted to check if the hum on mine was normal compared to other models, and then decide from there whether to keep it or not (I probably won't, as it's pretty unbearable.) Firstly - the hum is evident whether the standby is on or not. It takes a few seconds from power on to start humming, but once it starts it's there. It doesn't get any louder as the volume or channel changes. Secondly, the hum volume. With my iphone to the speaker, using a decibel meter, the meter reads 37.7db without the amp on, and 69.9db with the amp on but the standby off (purely the hum.) . Thats a lot of humming. I know that everyone says that it's because it's so small, but it's the same size as the JP-2C, which fits in reverb, three channels, MIDI, 2 EQ's, a boost circuit etc with zero noise, so I don't really buy that. Is this normal, or is this amp specially affected? I've emailed the PRS guys as well! Cheers all.