McIntosh-Keep the Classics or Sell for Newer Gear?

If you're happy with the performance I say hang on to it. I agree with Ces4x4 as far as keeping the equipment up to snuff. As far as taking the top cover off and writing down the cap values, the tech is going to be in there anyway and modern caps are generally physically smaller than old caps (the Elna Silmics are rather closer to the older sizes...). If the tech procures the parts and something goes wrong and takes something else out with it he's more likely to remedy the situation at no/less cost to you,than if you provided him with parts from an unkown source. Plus there are cases where experience dictates replacement with say a higher value or voltage, or a different type of cap altogether- perhaps a bipolar or film cap in certain instances.

keep it.

Hang on to it, but as far as the C32 is concerned, DO NOT ALLOW ANYONE TO EVEN OPEN THE COVER IF IT WORKS FINE.

Explanation: The C32 was McIntosh's first and only product to incorporate the then new Ribbon Cable technology, and the mfr of said cables was new and inexperienced: a ribbon cable (formally known in electronics as a FFC (flat flexible cable) is a flat ribbon of conductor laminated between two layers of plastic to form a wide paper thin cable with either pins or tinned conductors at either end).
GUARANTEED, the ribbon cables inside the C32 will be delaminating from heat and poor manufacture and once removed for service will split wide open like a ripe banana and be IMPOSSIBLE TO REINSTALL.

McIntosh NO LONGER CARRIES THESE proprietary cables nor are they available anywhere else(the new stuff is far finer/thinner and has more conductors, etc). I oughtta know: my first Mc was a C32 I bartered a computer repair for and spent over 400 hours hand making new cables for it so I could sell it on eBay. NEver again would I touch a C32.

McIntosh Service Authorized since 2005, so I speak with some background.

You make mention of the MA6600, absolutely love mine. With Mac gear you can't go wrong either way. But...having your Dad's gear is special. As it is working, buy some new music and add a new piece or two when funds permit and continue the legacy.

Happy listening.