I have an old 3155 integrated as well, in a secondary system for casual listening. No, it was never a contender for transparency but it is a nice integrated for a beginners system and you will pay much more for new equipment to beat it. After all, this is 25+ years old.
Due to this age it is probably wise to re-cap it. I did this about 5 years ago and it did come back to life and sounds fine again. Better than original? Who knows, I can't go back 25 years to compare, but it was definitely better after the recap than before. Cost me about $100 in parts (Panasonic FC caps from Digikey) and I did the work myself. It was a fun project, just be sure to go one part replacement at a time and replace exact values.
Enjoy,
Bob