This is reply by the designer of the thing, IMO he has much more credibility that guy in first link you posted,he designed one of my favorite guitar pedals and he has tremendous respect in guitar players world. BTW I can find rave reviews of said amp on this very board.
A rumor spread by some ill-spirited and jealous PPI engineers perhaps. The amp has a fail safe circuit which will allow it to operate in solid state mode if the tubes fail. This adds to the confusion. Why would I risk 25 yrs reputation with pro musicians, etc and not have the tubes operational?? Makes no sense.
so if you read some more you`ll see that rubes works in diode mode, therefore can be disconnected without significant change in sound. that what I read, I havent pulled tubes out of mine- according to butlet it`s pointless because solid state circuit will be hot anyway. Is US amp better- maybe, maybe not, it`s a matter of opinion and I`ve heard yours. we hacked that topic to the end we should stop, really. OP I apologies.