Somebody asked why ARC didn't "just include" auto bias in the i50. Because it costs. And it would then compete with the more expensive models.
I don't know if this is how they did t, but the old Classic 30, 60, and 120 amps used a servo...an inexpensive chip...to maintain bias once set. That's what Raven did on their $5k integrated.
Auto bias circuits have been done for years. But is the "auto" when it is static, while the tubes idle? What happens when you turn up music? Or tubes age? Or one tube goes a LITTLE whacky? Or maybe it was whacky when you bought the amp?