My TriodeUSA ST-70 has all JJ tubes; EF34Ls behind two EF806 and a ECC82 or sometimes I swap it out for a RCA 12AU7A, and a 5AR4.
It is important to note that I have a powered subwoofer system, so the ST70 is asked to only drive my extremely efficient Altec A5Xs from 80hz and up.
My major complaint is a lack of dynamic range. My other system is a solid state amp running a set of B&W DM605S2s. High dynamic range source knocks me over with that one. My tube setup sounds compressed across the range in comparison.
I am likely to replace all 8 tubes, but I’d like to get some advice as to whether a lack of punch is more likely to be determined by the driver tubes, phase splitter, or power tubes, or even the rectifier.
At this point I am leaning towards KT88s, hoping the reputed additional headroom will get me that punch I’m looking for but thought I’d run this by more experienced tubers before I take the dive.
Thanks for any advice.