The 2205 was among McIntosh's first amplifiers that had true-complimentary output devices (NPN and PNP), and as such is IMO vastly superior (much less notch distortion) to their first-generation solid-state amps that had quasi-complimentary (all-NPN) outputs. They also respond nicely output-transistor upgrades, to i.e. MJ15028/MJ15029.
That being said, the input section is pretty old-fashioned, and IIRC it has a separate internal preamp, because the circuit itself is kinda low gain. If you were to find a Mac amp just one generation newer (i.e. MC2255), they're MUCH more linear . . . Mac by this time was using a modern front-end on their already excellent output stage and autoformer. Maybe Audio Classics could make a trade-in attractive?
I'll second Usblues' advice on finding a top-notch servicer for your 2205 . . . getting vintage solid-state amps working well frequently means substituting some semiconductors, and it's important to have a good understanding of the circuit when this is done.
That being said, the input section is pretty old-fashioned, and IIRC it has a separate internal preamp, because the circuit itself is kinda low gain. If you were to find a Mac amp just one generation newer (i.e. MC2255), they're MUCH more linear . . . Mac by this time was using a modern front-end on their already excellent output stage and autoformer. Maybe Audio Classics could make a trade-in attractive?
I'll second Usblues' advice on finding a top-notch servicer for your 2205 . . . getting vintage solid-state amps working well frequently means substituting some semiconductors, and it's important to have a good understanding of the circuit when this is done.