On Mon, 15 Feb 2016 09:01:57 +0100, alpibucky
wrote:

Marantz superscope MS-30

I'd be surprised if the MS-30 had output transistors. These
multichannel all-in-one one units often just used a power IC for each
channel.

Sounds like you don't know if the output circuit is the actual
problem, here, or you'd be able to quote the part number from its
physical markings, on the assembly.

RL