I use my Mesa D800 with an Ampeg 810 (not mine, but shared from another band) in the practice space and the same head with my Fearless 212 for shows. I have the exact same experience as you. The 810 annoys me in a small room and my Fearless at gigs is just better in every regard. I constantly think, why is my sound so muffled? What frequencies do I need to decrease in this room to get it sounding good? After a few times of switching between the two, it's all good now. It's basically real world experience in using rental/provided rigs at shows and how to get a usable tone for YOU on random stages.