MarkBass amps have a really high gain input section (low sensitivity). I owned two and both were the same. I could not turn the input level past the 3rd dot with a passive Fender bass or it would clip. This was the LMIII and the TA-501 amps.
Also the master volume on both these amps stops functioning at 12:00. Anything past 12:00 and you get no increase in volume.
I think these amps were designed for low volume playing but giving the average Joe the impression that they are really loud.
Set the input so it does not clip, set the master on half way and if this will not do it for you, you need a different amp.
Hope this helps.
