Hi all this is my first post

I am having problems with my volume on my amp i am playing through the MH-550 half stack at 400watts, the amp is loud as hell when playing without the band although as soon as the band kicks in it fades into background it seems like i am having to turn the amp to almost max, and fighting for volume, please if anyone out there is having this problem could you please offer some suggestions the amp just does not seem to have the same volume as when i first brought it home.