Already know about the MC board. Does it work with output devices that are in production now? I know I have some bad output devices as well as problems with the driver PCB. I had originally done the film cap and metal film resistor mod, and got several years of service out of the modded amp. I had replaced the output devices in one channel with the BUZ03, which worked for a while, but it turns out that these are not long term reliable in the Hafler, and that is the channel that developed DC on the output. I am really not interested in mucking around with the stock Hafler driver boards any more, and would like to stuff some more contemporary innards in this great chassis.