My mg 100dfx combo which I bought last week seems to have a bit of a vibration/rattle when you play at a higher level mainly using palm muted chords. Anything to worry about? I was using it in my spare room tonight and I didnt notice it at band practice the other night.
Mabey cause the amp sucks. Im not trying to be mean but you should take it back and try some different amps.
"Blues is easy to play, but hard to feel."- Jimi Hendrix
Your amp is built out of low grade equipment, so this is kinda expected. Really not much to worry about though.
Guitar: Ibanez Rg 2ex2/ with Dizmarzio Super Distortion
Amp: Peavey Valveking 212 (replacing soon)
Pedals: Planet Waves Tuner, Boss DS-1, Digitech DF-7, MXR-108 EQ