My introduction to ARC's build design and parts quality was when I turned on my new SP-3 for the first time. It immediately made a popping sound, and I learned what a burnt resistor smells like ;-) . Years later, Tom Carione showed me the scorched circuit boards inside all the ARC power amps that had been traded in at Brooks Berdan Ltd. for Music Reference, VTL, and Jadis amps. Power tubes mounted on a circuit board?!
I so wish I had been in a position to get myself a pair of Roger's ESL loudspeakers and direct-drive OTL tube amps. 5,000 volts delivered straight from the tubes to the ESL stators. No power amp output transformer, no ESL step-up transformer---ultimate transparency! I suppose that design has died with Roger.
In his final (third) version of the RM-10 (still referred to as Mk.2, but now 25w/ch Class A), Roger DID go to auto-biasing. He told me my RM-10 (original 35w/ch version Mk.2) ran in Class A up to 15 or so watts, which is where the original Quad ESL has it operating most of the time (especially when high-pass filtered at 100Hz). Also owning an RM-200 Mk.2, I just have to get myself an RM-9 ;-) .
Roger stated he found power amps much more interesting than pre-amps, perhaps why he is better known for the former. As does Nelson Pass, Roger felt that whenever possible (system gain structure, impedance matching, etc.), a passive pre is preferable to an active one. He wasn't driven as a businessman to fill a market demand, but rather to create a design that hadn't been done before. 35 watts out of a pair of EL84's, 100 watts out of a pair of KT88/6550's (into both 8 and 4 ohms!), both with around 10,000 hours of tube life, that he certainly did. And with no burnt resistors or scorched circuit boards ;-) .