Spare right & left circuit boards would be nice to have. My former EX4420 was a nice sounding amp I enjoyed for over 20+ years. It got rather hot and parts inside degraded over time, hum. Had the boards repaired multiple times until I sold it for parts, unfortunately. ATI amplifiers bought B&K brand, and designs, seemingly no leftover parts. Called them multiple times with little luck or interest on their part.
