[hal55]

I have a 2 year old Mk111 and have replaced the driver tubes with Voshkod 6J1P-EV. It works really well but I'm tempted to try and get that "last 15%" that I've seen referred to. Can anyone tell me what power tubes might work best with the Voshkods and whether the somewhat expensive output supertubes are worth it? My Mk111 is used only as a stereo preamp driving my Jungson poweramp.
Current power tubes are of course the stock ones fitted with the unit. By a long shot, can the output RCAs be replaced with balanced XLRs? Anyone done this?
Thanks

Hal55