SANSUI RA-700 Reverberation amplifier. Very close to mint.

Reverb on some songs is like a cowbell—once it hits your ears, the only answer is more. You'll have as much echo as your tape deck can handle with this $90 . To top it off, this Japanese unit has a rainbow LCD display—a trippy visual punctuation to show where your reverb time is set within the 1.9 and 3.2 second range.
In their late-70s/early-80s heyday, Sansui was a good choice to boost a hi-fi system. This one's blinking lights and walnut grain finish might also punch up the den's decor.