just purchased the M100,uses KT88,love the sound especially the mid range,very open and seductive the highs are very smooth, bass is tight and deep, love the sound,use to run Belles 350A ref SS awesome amp, but it was just too powerful for my condo, Question: besides the KT88 witch other tubes are compatible with this amps, and witch brand should I try; also drivers, and rectifiers tubes witch are the best you have try:
