I'm considering a Fryette power amp to pair up with my Ultra for my live rig and would like to hear some comparisons or experience from anyone who is familiar with both models. Do they sound drastically different from one another? Do they color the preamp tone much, especially in the low power modes? I'm sure the 50 watt model is more than enough power for my needs, but if the 90 watt model has any advantages tone-wise, I'd like to hear about it?