It really depends on the speakers you intend to use the amp with. A Yaqin MC10T push/pull will output a little over 50WPC and work fine with your average (87db@1m) speaker. It has plenty of room for improvement with tube rolling, coupling cap and volume pot upgrades which allows it to compete with some far more expensive amps. If you're running some efficient speakers they're always the Oldchen EL34B SEP amp which outputs 10WPC. Drives my 96.5db@1m Dayton USA PS220-8 speakers very nicely. No need to really upgrade anything in this little amp as components are already of a decent quality. It benefits from tube rolling though. I run all Soviet eta Russian tubes in mine.