just my 2 cents here - I've owned 2 Cullen modded and 2 unmodded GCC amps over the years. All are totally bulletproof, but the Cullen modded units are much superior sonically, really nice sounding and maybe the best choice among Icepower amps. I use one in my recently upgraded office rig, and am very pleased with it. The "preamp" gets short shrift, but it is incredibly clean and very flexible.