from my experience with kt90's kt88's/kt150's. there is only lsight gain in sonics over each, the 88's beat out the 90's, the 150's beat out the 88's, not by much, IOW I'd be quite happy with 88's vs the kt150's i bought at 75/each. x 12.
also i note, a 88 is a 88 is a 88. The sonic difs in power tubes is so ~~miniscle~ as my baton rouge tech guy uses that word,,, = all 88's are equal.
but now in 300b tubes there are some incredible looking, but expensive designs, = the mesh plates etc.
hummm, tough call.
if i were you i'd sell the QS and go with a new 300b amp, then later on upgrade the stock 300b tubes to mesh plates. Line Magnetic anda few other chinese labs have interesting looking designs. for a very reasonable price. My fav chinese lab is Cayin. Made by Spark. they offer a stunning 300b design.
hope that helps.
also i note, a 88 is a 88 is a 88. The sonic difs in power tubes is so ~~miniscle~ as my baton rouge tech guy uses that word,,, = all 88's are equal.
but now in 300b tubes there are some incredible looking, but expensive designs, = the mesh plates etc.
hummm, tough call.
if i were you i'd sell the QS and go with a new 300b amp, then later on upgrade the stock 300b tubes to mesh plates. Line Magnetic anda few other chinese labs have interesting looking designs. for a very reasonable price. My fav chinese lab is Cayin. Made by Spark. they offer a stunning 300b design.
hope that helps.