Retubing an ARC VT100 mkll


Thinking of tube rolling my VT100 mkll. Currently using EH for both the 6922 input and 6550 output tubes. Less than 800 hours on the entire set, so its not that I need an entire retube, just looking to improve the sound if possible. What would give the biggest improvement, changing out the input or output tubes to KT88/90? Bear in mind I would need a closely matched OCTECT of either so bizarre/rare vintage tubes are out of the question. Thinking of Gold Lions or similar, any thoughts from the scholars?
spinaker01
I have a Cary SLI-80F1 integrated with Genelex KT-88's and like them very much. As for the 6922 varients I use Amperex 7308's from Upscale Audio and again really like these tubes. I know you said no NOS tubes but these were a vast improvement over the EH 6922 tubes. For current production tubes you may want to try the Genelex here as well but they are kind of costly IMO and I have never tried them so I can't comment on how they sound in my amp. Otherwise for reasonably priced current production tubes I have had good luck with the EH tubes.
I believe there have been a few issues with the 6550EH's and ARC gear. They are currently using the Sovtek 6550WE. I would continue to use the 6922EH as that is the tube that product was voiced with.