Cary SLI-80 tweaks and improvements?

Hello all,

I have an older Cary SLI-80 that I'm trying to find a path forward to a wider sound stage and improved dynamics.  In comparing it to my Decware Taboo, yes, it has a boat-load more power available, however, the Decware has a much wider sound stage, better channel separation and decay from instruments like cymbals, compared to the Cary.  The channel separation is much better on the Decware and this is especially apparent with songs that feature heavy panning from left to right and back again.

The Cary is running vintage Bugle Boy 6922's, vintage Sylvania 6S7N's, and Ruby 6550's.  

I have been looking at a couple of different paths forward:

Moving to EL34's or another power tube?

Upgrading the internal capacitors such as upgrading to the F1 mod?

A combination of both?

Any other ideas to try to capture the performance of the Decware are welcomed.

Thank You!