I owned one of the 40w x 40w, stereo chorus Valvestate combos with two 12" speakers - made around 1994 in the UK. I had a number of problems with pots. First of all they got crackley really fast; and because they were mounted right on the board I also developed a number of cracked solder joints where the pots were mounted. I only owned it about 9 months before passing it on to my brother who kept it alive for another 5-6 years after eventually having all the pots replaced.