I have the Marshall VS275 2x12 combo, and this thing sounds amazing at any volume. It is also very, VERY loud! Plugged up to a 4x12 Marshall cabinet and it is so lound you can't stand it. I'm not too familiar with the MG series, but the VS sounds good at any volume, (at least the VS275). I used to have a VS100R 1x12 combo and it sounded good, but got real muddy at high volumes. You might want to try adjusting the eq when it's cut up. If you set your eq at low volume, that's where it will sound good, and not so much at high volumes. So I would suggest turning it up loud and adjusting the eq and just go from there. Don't forget about the gain, and if yours has it the presence. Both can have a big effect on how you sound depending on your volume. Hope this was some help. Remember, be patient and don't be afraid to play with every knob on it 'till you find the sound you're looking for.