My rig consists of a 1980 JMP 2203 and Marshall 1960B cab. Guitar is a 1974 Gibson Les Paul loaded with Bill Lawrence L500 pickups. I've come to notice that when I play with the amp cranked (master volume 9, pre-amp volume 8) it sounds amazing but when the master volume is under 4 it sounds very shrill with a harsh top end. Is this a result of 75 watt celestions? I like how they sound at loud volumes. A lot of bottom end and very tight. However low volumes it just sounds shrill and weak. I've heard videos on YouTube where people only have their master volume at 1 or 2 and preamp 10 , and it sounds much better than my amp with the same settings. I've been thinking about trying out the 25 watt Greenbacks or maybe trying an X pattern of the greenbacks with the 75 watt speakers, but I don't want to loose that tight clean sound the g12-75's give me and the bottom end which I really like. Any suggestions? Maybe I should try changing my settings when I play at lower volumes and roll back the mids and the treble? I like bright tones with a lot of midrange but also want it to have a tight bottom end without the shrill highs.