also had general idea of stk modules as being very bad . trough my hands i passed 20 or so stk based amplifiers/micro systems, that have gone bad. starting with very old stuff with no replacements ,to modern systems. modern ones seems to be little better in general but i see more complex protections around modern stks.
all other amplifiers i checked had common bugs(dry caps ,dry solder,open resistors) where stk based amps tend to have at least 2 modules changed before usual bugs appear.maybe its cheap goo that they put becouse they need lot for such big area ? or is it bad luck to 20 different people i know also.
to op.. i had similar question and someone told me to use bucking transformer for lovering voltage. so you can use any chip you would like.