I have a Meyer Sound 833 control unit on my bench. It has a weird fault that appears to centre around a 15kHz oscillation that affects one channel, directly, but is bleeding through to the other channel.
Meyer Sound refuses to supply a schematic. They will repair it for a set charge of US$592.50 (nice round figure). That's a bitter pill to swallow, but it gets worse. I (and my customer) are here in Australia and I figure on the freight charges to blow that figure out to around US$1,000.00 or so.
I am hopeful that someone has some experience with this product. Maybe even schematics.