Svetlana Winged C KT88s, Mullard CV378 rectifiers, National Union grey glass 6SN7s, Amperex Bugle Boy 6DJ8s. This complement gives me a warm yet resolving enough sound for the variety of classical music I listen to--choral, opera, symphonic.
I often change the 6SN7 pre-driver tubes to affect the sound:
1) Tung-Sol roundplates for more dynamics and treble extension;
2) RCA VTI-231 black glass for more relaxed and open sound (in my system), which is better for piano music;
3) Brimar CV1988 for a very lush sound.
I've changed the power tubes in the past:
1) RFT EL-34s for a more spacious sound with better imaging, though much lower power;
2) Tung-Sol 6550s black plate, no hole from the 50s for wonderfully sweet upper mids and extended, clear trebles. Fabulous for opera sopranos but not that widely applicable to a variet of music in my system.
3) Sovtek 6550s came with the amp, but I never found music I liked to play with them.
I often change the 6SN7 pre-driver tubes to affect the sound:
1) Tung-Sol roundplates for more dynamics and treble extension;
2) RCA VTI-231 black glass for more relaxed and open sound (in my system), which is better for piano music;
3) Brimar CV1988 for a very lush sound.
I've changed the power tubes in the past:
1) RFT EL-34s for a more spacious sound with better imaging, though much lower power;
2) Tung-Sol 6550s black plate, no hole from the 50s for wonderfully sweet upper mids and extended, clear trebles. Fabulous for opera sopranos but not that widely applicable to a variet of music in my system.
3) Sovtek 6550s came with the amp, but I never found music I liked to play with them.