I wouldn't run PA speakers on it for studio monitoring...though I hear the Grateful Dead used those for PA amps. I don't know if they had modifications, or not...as in...something different than the RCA inputs? Anyway, I'd keep it. Maybe even just get some good home stereo speakers, and listen to your stuff on that to get an idea how it sounds on a home stereo?
Then again, if you're short on cash, and REALLY need something else, there it is. You may regret selling it, though, unless you buy a vintage piece of something else (guitar, amp, mic, etc.) How many things made these days do you figure will command the same lust-factor after decades, and retain (or even gain) value, because of their quality build, reliability and great sound? Your average new Pioneer, Onkyo, etc. is going to be cheap yard-sale stuff in 10 years.
That's just my opinion. I vote "keep it".