Tube rolling in the Cary SLI-80 Signature

Interested in hearing about your experience with rolling tubes in the Cary SLI-80 Signature -- different new-manufacture and NOS -- especially at it relates to Merlin TSM-MMI monitors. Also, tube rolling in the Ars Sonum Filarmonia. Are NOS a marked or marginal improvement, and if so, how so?
I use a Cary SLI-80 in a secondary system with Merlin TSM_MM and I found this tube compliment to work very well and is very musical.

2 ea - Amperex 7308 Input Buffer Preamp
2 ea - Sylvania 1952 6SN7GT "Bad Boys" Pre Driver/Phase Inverter or Russian metal base 1578
4 ea - Re-Issue Gold Lion KT88 Output Tubes
2 ea - GE 5U4 Rectifiers

I run the amp in triode mode and it sound is very balanced with the Merlins.
I have only had mine a couple of months, but following is what I have settled on:

white label, gold pin, Amperex 6922s
Sylvania 1952 3 hole bad boy 6sn7's (sometimes roll in TSBGRP but like the BBs a little better.)
Re-issue gold lion KT88s
Tung Sol NOS 5u4g

Of all of these, I would say the 6922's made the largest difference in sound quality - quite a jump in top end extension and dynamics / detail with these. Next the Bad Boys.

I have been using Proac Studio 140s but should receive some Silverline Sonata IIIs in a week or two.
Thanks for the input. How does one identify a "bad boy"?
It appears the Sylvania Bad Boys are most peoples choice for a 6SN7 in this amp!
Try some 5AR4's in-place of the 5U4 rectifiers.. Sovteks can be had for around $15.00 a piece...