OK. I have a second hand Single Recto that I cannot power up as I don’t have a step down transformer yet (live in Australia bought from US) . I have read the spiel from Randall Smith about bias etc and how Mesa tubes are set to stricter standards than many others. The amp I have has some Russian tubes, I can’t remember the type but with red writing. Clearly not Mesa tubes anyway. What is the general opinion or experience with other tubes in Mesas? Is Randall trying to push his own gear or do Mesa tubes sound and work better? I enquired with my music shop about getting a set of matched Mesa tubes but even he said to wait to hear the amp before changing them as in his opinion may people preferred other tubes. Im talking about power tubes here too.