It can be a rabbit hole for sure but if your system does not sound great I would hold off on buying anything else until you research and experiment as to why specifically it doesn't.
electronics, tubes, speakers and cartridges take many hours to reach full potential.
older electronics may need to be checked for their major components to be in spec- especially power section capacitors.
a live room can cause fatigue as can improperly positioned speakers.
how is your phono cartridge and phono preamp ? this is an area that usually has a lot of potential for growth including adjustments and proper cables.
make sure your system is fully mature, in spec and optimized in your room and then make some evaluations.