I have some "Holy Cow" organic cleaner I'm going to try.  It's non-toxic and claims to be quite gentle on surfaces.   
 
  
 
What kind of speaker would I mate with it?  When I acquired all this Mac gear about a decade ago, I regularly spoke to a tube head who built his own single ended triodes.  He didn't have much interest in amps that put out more than 13 or so watts, but I recall he referred to the MC-75 as a "big honking pentode."  He didn't have much advice for speakers I'm afraid. 
 
Sadly(?) I don't have a cat.  My housemate is an asthmatic, and he's pretty allergic to them.  I thusfar haven't sprung for one of those $6000 GMO hypoallergenic kitties.   
 
Tonight, while I'm waiting for my mix to upload, I snapped a few shots of the C-22 preamp.  This one came out best: 
 
   
 
It, too could use a good cleaning.  I had hoped to integrate it into my rig as phono preamp, but the logistics are something of a nightmare.  There's no room in my rack for the C-22, and the cords on my Technics aren't log enough to reach it in any practical arrangement.  It looks like if I tore apart my entire rack, removed the Hafler amp, and put the power conditioner all the way on the bottom, I might have enough room to shoehorn it in.  That is a process that could take several hours, and not something I want to consider at 11:30 at night.  
 
While writing this, I took a shot of the back: 
 
   
 
The RCA jacks are in surprisingly good shape for being nearly 40 years old.