What's the next upgrade step??

You can experiment with different brands of tubes. Also resistance loadings
if your unit allows.

You're system is pretty well balanced. Are you looking to replace the whole thing? If so, what's your budget? If you're willing to go for it, I would suggest moving up in the Basis line to the 2000 and going with their Vector arm and pairing it with one of the Transfiguration carts but that will run you over $8000 list. You could do it in steps in just about any order with good results. In your case I would prioritize the arm, then cart, then table.

On another tack, you could try TWL's lead outrigger weight tweek for almost nothing - effective, reversable and fun.

dealer disclosure.

I I second the TWL mod:

http://forum.audiogon.com/cgi-bin/fr.pl?eanlg&1032024188&openfrom&2&4#2