The upgrade moves the Premier 11 close to the performance of the LP 70. The amp becomes more neutral, alive and, as Ed said, better microdynamic, detail and soundstage. The LP 70 maybe CJs most neutral and musical amp. And, when you get the amp back, it is basically new. So, sonically and physically it make sense. From an economic perspective: a used Premier 11 will sell for $1800. Add $1400 for the upgrade = $3200. A new LP 70 was $7500 and you can get one from Spearit for $4800. I have not seen any used ones for some time. So, interms of dollars and sense you are ahead of the game. But then again, the Premier 11 is nice as it is. If you want to get more from what you like, then this is one option. Upgrading your preamp will cost a lot more.
Is CJ's T Cap upgrade for the P11A worthwhile?
Love Jazz, female vocalists, classic rock, prefer live recordings, listen at moderate levels. CD: Sonic Frontiers SFT-1, D2D-1, Processor 3; Amplification: CJ Premier 16 ls2, Premier 11A; Speakers: Nautilus 805 w/ stands; Interconnects: Siltech SQ 220i Classic Anniversary; Speaker Cable: Siltech LS88 Classic MK2