Kt120 Vs kt90 Sound characteristics

@stereo5 I’m an ex EL34 diehard myself. Over time learned Tung Sol KT120s can sound really good with at least two factors present. Lesson learned here before making premature judgement. Burn-em in at least 200+ hours, no joke. They DO settle in nicely, same with my KT150s changed at 300hrs. I learned this from Conrad Johnson owners too. Today I run KT120s today in my mono amps. The second is a game changer for digital front-ends. Making sure a really good digital source/dac is used along with a clean and quiet power supply. I like the sound better than my former EL34 amps now. As for KT90s, I won’t digress, there are several reviews indicating few amps run KT90s well, and most moved on to KT120s anyhow. My KT150s sit in their boxes. KT120s can sound good, given a fair chance in well designed amplifiers, good transformers, caps, bits inside.  

@stereo5 Maybe the second and third generation was better?

A short reply of yes, maybe.  Not totally sure but doing some quick research, if yours is the first generation, looking back found some audiocircle posts with members in 2013 liking the later Tempest amp with KT120s better compared to the early Chronos, sounding "strident". iirc, reading about this a few years ago -  there were  design and component improvements with the gen II, III, also noted several trying different 12au7, 12ax7 tubes in Chronos hoping to achieve a more lush sound.  I wonder if you call Rogue next week and ask if they could offer a means to upgrade yours to the later versions somehow.

Might be a worthwhile inquiry. Best of Luck.