This may sound too simple, but if you really like your BAT VK-75SE, and you've heard and enjoy the 6H30 tubes, why don't you just try/buy a BAT VK-51SE and be done?
FWIW, yes, I agree that the 6H30 tubes are more dynamic and powerful, however, they do seem to lose a bit of that midrange bloom that tubes are famous for, IMHO. They do blend solid state and tube attributes, though to some, this is not a good thing. Perhaps it's because there are no NOS 6H30 tubes to roll, as I've found Sovtek 6922's to sound a bit sterile as well compared to NOS Amperex/Mullards/Siemens etc.
FWIW, I would try rolling the 6H23's with the Valvo and Tungsgrams, since you already have them. It can't hurt.
Happy hunting,
John
FWIW, yes, I agree that the 6H30 tubes are more dynamic and powerful, however, they do seem to lose a bit of that midrange bloom that tubes are famous for, IMHO. They do blend solid state and tube attributes, though to some, this is not a good thing. Perhaps it's because there are no NOS 6H30 tubes to roll, as I've found Sovtek 6922's to sound a bit sterile as well compared to NOS Amperex/Mullards/Siemens etc.
FWIW, I would try rolling the 6H23's with the Valvo and Tungsgrams, since you already have them. It can't hurt.
Happy hunting,
John