There is money burnin' a hole and need some advice on an upgrade. Most audiophiles don't have a problem I imagine, but I can't decide what to do next.

Receiver--AKAI (upper end late 80's model, when they used to be something:>) 120wpc @ 8ohms 0.03%thd 100db s/n
DAC--Pioneer PD-M650
Cassette--Nakamichi BX-100
Turn table-Kenwood
Mains:AR AR318PS
SPKR cables:Monster XP
Interconnects:Monster standard and Phoenix gold premium