If you like the speakers, as I did, the greatest positive change would come from three things:
1. Room treatment. This is the biggest lever, potentially, but also involves the greatest cost and trouble. But it's 50% of the sound. Lots of help out there.
2. Vibration control over the speakers. Something like a Townshend platform. I have used these with a variety of different speakers and the difference is very noticeable -- defeated my skepticism. I was willing to ship them back for a refund but they made an undeniable positive difference. More than cable changes or tube changes or almost anything else.
3. At least one good subwoofer, possibly more, carefully placed and tuned in to your current speakers. Not a cheap or easy enterprise to do correctly but it is magic once it clicks in.