marantz 4300

That is a nice old receiver for a vintage or second system. I keep an old Marantz 2215b around for that same purpose. They are very smooth sounding and pleasant to listen to, even though they are not as resolving or detailed as some newer gear. With old Klipsch speakers or other horn speakers, they are the next best thing to mega-$$$ SET amps. Don't pay any attention to negative and degrading remarks from others on this site, if it sounds good, listen to it.

Put a pair of speakers in the Garage and hook it up there.

Probably might need some cleaning and recapping at this point,
but if it works and sounds good to you I would use it.

Don't pay any attention to the negatives some folks bring up.

Kenny.

It's a defunct format that is a nostalgia piece at best these days.

Is it is it worth keeping? well, that depends on what you intend to use it for .....

-- Workshop, garage, cottage ambience filler "C" or "D" system ...... sure..... why not ?

-- home audio 2-channel performance: .... not really. Sonically it gets smoked by even modest integrated amps today with the improvement in design and components.... not even close. I had a MARANTZ 2245 and JBL L100s in my dorm during a misspent college youth . They were fine for their time, but that does not carry forward to today.

I wouldn't waste time and money recapping it ... the price to performance reward just isn't there. And a quirky 4-channel format is no benefit in trying to sell it to anybody other than a limited internet arena of nostalgic  freaks.

"Vintage" in audio is NOT the same as in fine wines. It just means old and failing .