I've been using a 500X for a couple years now. I had to quit playing for a while because of my back and other arthritis complications but I'm stating up again. The problem now is, I sold my 1966 Pro Reverb and the only amp I had to play through is a 1960's Silvertone 1482 combo. A great amp for pedals, but not so great for the 500x. I've been searching for something to use for less than $1600 (what another '66 Pro would cost) so just for the fun of it: I hauled my Ampeg 100 watt combo bass amp over and plugged into it. Very, very promising except there was a harshness on some notes when I was doing the lap slide stuff. I yanked the grill cloth off and discovered to my complete surprise there is a Piezo type tweeter. I pulled that sucker out of there, put a 100 watt heat sink resistor load on and WOW!! sounds better than my old Pro reverb and it's FREEEEEE!!!!!