Just read your comments and question. I've been back in Hawaii for the past month with minimal access to a PC (and no HiFi) so sorry for the delayed response.
My progression of Shindo amps were initially a Montille EL34 (paired with a Monbrison preamp) then a Cortese F2a (paired with first a Monbrison then a Masseto) then I moved on to pair of Lafon WE300B monoblocs (paired briefly with the Masseto then a Vosne Romanee). Speakers throughout this process were a pair of stock Altec 846A Valencia's. At every level, it was a pleasure to listen to my system. The level of detail, coupled with, for lack of a better word, a certain emotional connectivity to the music. If I were to stay at a particular level in the "journey", I wouldn't feel my system lacked for anything. The Monbrison/Masseto and Cortese pairings were particularly satisfying. I listen to jazz, classical, R&B, R&R, women vocals, Hawaiian slack key and the system pairings reproduced these genres very well. The Cortese is a great SET amp. When that was inserted into my system, plucked strings and dissipation of the crash of a cymbal took on a whole new dimension, well recorded vocals had that "in the room" quality. Background noise was minimized, almost black. There was none of the fatigue I had experienced with high powered SS equipment paired with less efficient speakers that was the earlier HiFi path I had taken.
I would have stayed with Cortese but the Lafon WE300B's became available and that was my "mad splurge" for the year. Earlier this year I acquired a pair of Corton Charlemagne's that use the EL34 tube and they also sound great with my Valencia's. My plan is to alternate between the Lafons and the CC's as soon as I re-insert the Valencia's back into my system (I'm currently running a pair of Quad ESL 57's which pair up better with a pair of Quad II monoblocs). I think my system is set, except for a move to the Giscours should a reasonably priced, gently used one come on the market.
Best wishes to you and your audio journey!