well it's a close one for me, i felt the mesa was more versitile but harder to dail in. the soldano easier to dial in but not as versitile as the mark IV. both very tight, and articulate. the marks bottom end seemed to be alot nicer, but the soldano didn't have the depth switch and that could have made a difference. the soldano was very nice at low volumes the mark not as good at low volumes as the soldano, but i don't really play at low volumes. so i guess i'm gonna say the mark IV because of the versitlity factor but they both sound really nice. i'm just looking to see what everybody else opinions are, to see if other people feel the same way i do. you know the slo is supposed to be "the" amp, but i feel the mark is better, am i crazy but i just feel like the mark has better tones in it.