I emailed Nik and he informed me that the PT is rated at 6A in these amps - and will cope with the extra current of KT66 tubes - it will of course run a little hotter but at the moment the heat from the Xformer is not great ( I have had several amps which seem to run much hotter including an English made Mxxxxxxx amplifier
Quick reply to my query from Nik - great service for great amps!
Rock on