Questions on KT150 tubes

What sonic differences do you hear in the KT-150s compared to the KT-120s? I have been running KT-120s in my Emotive Audio amps for a couple years but no tubes last for ever. When replacement time rolls around, I am wondering what to expect if I get 150s instead.

I have the same Jolida amp as the Wolf_Garcia. I had the Tung Sol KT-120s and later got to KT-150s. To me with the Tung Sol KT-150s in place I've got the big and sweet midrange/highs of an EL34 tube with so much for oomph bass wise. The bass wasn't boomy either like when I had JJ-KT88s in my amp. To me when I had the Tung Sol KT-120 in my Jolida I found the music to be ok sounding not a good experience like the Wolfman had. I ended up getting NOS GE 6550 tubes in the Jolida and liking that sound. When one of those tubes blew up on me I then went for the KT-150s after having long talks with Jolida techs to ensure the amp would survive.

My KT150s have been in my amp long enough to erase the  memory of the tubes preceding them.

2000 hours on 120s seems to be about half or less than I got on mine and I had my ear on them looking for any sign of age near their end, and removed them as soon as I detected any tonal weakness (which was minimal but it seemed clear they had done their job)…I bet they had 5000 to 6000 hours on them, and I expect the 150s to last at least as long so we'll see.

I also own a Primaluna Dialogue Premium HP integrated amp.  I play vinyl on my Pro-ject Extension 10 and listen through the Volent VL-2 monitors.  I bought the Primaluna with the stock EL-34 knowing that I would swap all the tubes out upon set up.  I did.  I replaced all stock Primaluna 12AU7 tubes with NOS Telefunken.  Now I have a HUGE soundstage, incredible detail, and 3D imaging.  I replaced the primaluna stock EL34 tubes with Shuguang Treasure KT88-Z tubes.  Wow!  Talk about real bass slam!  These KT88s also offer very extended highs and a natural mid (female voice).  Several LAOCAS friends have come over to the house and have thrown everything they had at the system to find fault with it but to no avail.  Very happy with this tube set up.  I did run the EL34 tubes to compare with the KT88.  While the mids in the EL34 tubes were very lush there was a distinct lacking of real bass snap.  So, I am still searching for the Holy Grail of sound -- like we all are.  I spoke with Kevin Deal at Upscale Audio (Primaluna importer) and he said that he is running the KT150 tube in his Primaluna Dialogue Premium HP integrated.  Kevin affirmed this thread -- that the KT150 has incredible bass slam, very well extended highs, and well tempered, natural (not sweet) mids.  Because the Primaluna runs the power (output) tubes so easy (8 tubes for 78 WPC vs. the 4 tubes in the Ayon Spirit III) he says that they may last 10,000 hours.  So, for the money the KT150 seems the tube of choice.  Just hoping that Santa reads this post!