Nordicnorm,
Congratulstions! You had navigated yourself toward the same set-up I have. Sony S9000ES into a Teac 501. If you still have that equipment, here is what I have that takes the music to a "whole nother level".
In-between the Sony and the Teac, I inserted a Wyred-4-Sound Remedy Reclocker. To maximize the Reclocker, I purchased an iFI power cord to upgrade the stock cord. The power cord upgrade is a "must".
The resultant sonic improvement nocked my socks off. It added a great deal of extra detail, helping to individualize the various instruments playing ensamble. The added clarity also added a great deal of presence, imidiacy, and slam to the music that I never had before. Not louder, just way more noticeable.
While it added a lot of detail, it didn't make things too sharp, especially in the upper mid-range and the upper frequencies. So vocals and transients didn't become brittle. Soundstage was improved ever so slightly - just a little more depth.
So, if you still have that old equipment you might try the Reclocker. Like I said, it was a huge upgrade for me.