@moose89 you might look over some older Agon threads on this, a few bits of info here and there about 8-10 years back. fwiw, I owned a new/upgraded SLI-80 Signature myself. Kind of had to go overboard with mine to get it to sound how I wanted it. The stock EH KT88s were okay, not great. Some on Audiocircle will call them "bad" sounding. New Genelex Gold Lyon KT88s were better when paired with proper 6SN7, and proper 6922s. A local tech friend made some internal upgrades on my new SLI-80. I put the stock EH tubes in the box and saved them for amp resale time. Truly enjoyed my fully upgraded SLI-80, and would have kept it with the right efficiency speakers. Just needed a little more drive for my room, setup.
As I recall, you won’t necessarily get more power with KT120s in the SLI-80, however maybe a tad more drive on the bottom end, and a different type of midrange you may/not like as well as with really good KT88s in your amp. A possible tradeoff. While Cary may tell you it’s okay to run KT120s in the SLI-80, I don’t believe it’s optimized for them, really good KT88s can be the sweet spot in THAT particular amplifier. Circuit design, transformers, plate voltage, different in these amp. Can be design/tube specific.
The other CAD-120S amp was optimized to run with KT120s. While I run KT120s or KT150s in a different brand mono tube amps today, bigger transformers, higher plate voltage (just different), imo the SLI-80 can sound very nice (more musical) with upgraded KT88s, 6SN7s, 6922s and higher end coupling caps. Also, can share the SLI-80 sings its best when paired with the right speakers, a little higher efficiency speaker helps with that amp to get better drive out of it.
- Did you go for the standard SLI-80 Signature version or opt for the coupling capacitor upgrades or anything above std stock build?
- What speakers are you running with your SLI-80 now?