A similar approach was advocated by the designer of the Audiopax 88- which had two mirror image amp circuits in each monoblock and a pair of user adjustable controls to adjust bias- 'Timbre Lock' was the name of the feature. I had a pair of those amps for a while, and while I don't remember using different brands of tube, I do recall that there was a 'zone' in the adjustment range where the amp seemed to truly 'lock in' on a particular speaker set up.
Matched & Balanced Can Kiss My Euphemism
Good tubes are like good components: The only thing wrong with them is "sins of omission". After years of trying to match and balance everything I've finally found out you can pair different brand tubes to complement each other with fantastic sonic results and the only downside a slightly weird but still coherent soundstage. Sound is more important to me than vision. Not posting this for an argument, just wanted to share the wealth. If anyone's interested, I've had great results pairing a Funkwerk Rft Ecc82 with a Bugle Boy Ecc82, and a Telam el84 (airplane cooling fins) with an Rft el84 (Funkwerk, with the mickey mouse ears). These two combos have given me the air and sweet, extended treble of the bugles with the wonderful tone and PRAT of the Rfts. And the ethereal beauty of the Telams. With no downsides apart from the slightly wacky soundstage. Obviously if you have a million tubes to roll you're in trouble but my system only has seven tubes and if you're in a similar boat I strongly recommend mixing it up. Anyone have similar tube synergy stories?