Which amp would you choose for a JBL 4367 setup?

I am late to this thread but want to share my 2 cents. I have owned the 4367 for 3 years and paired it with more than two dozen amps. In my small 13 x 14 ft room, a Cyrus 6 XPD beat all other amps hands down, including a pair of Cary 805 RS which is supposed to be the best tube monoblocks for high-efficiency speakers and cost 10x more. But when I move to a large room 19x25, the magic disappeared and the little Cyrus started to show its weakness. So I guess the bog woofers interacting with the room is a major factor as well. Talking about small tube amps 30-40 watts with high current, I have tried both Unison Research S6 and Finale Audio F-120 Mk2, both sound warm and musical but a little slow and disengaging. I guess the big woofers just need a higher dumping factor to stay under control. Talking about high power solid state amps, I tried Krell 575 XD which is designed by people from Mark Levinson, however they were never a good match. I got fairly good sound with a Vincent SV-700 hybrid, but I simply miss the magic when I had the Cyrus 6 XPD and 4367 in a small room... all said, you have to try and I wish you good luck, and the room plays a major roll as well, not just the speakers, or the amp.

line magnetic lm-508ia 300b 805 should be very good,and the price is under USD4000

Very important to get warrant when you buy the amplifier.

One good thing about the Kinki EX-M1 is that the unit has the input stage op-amps mounted in sockets, so you can play around with swapping different op amps to change the "voice" of the amp just like a tube amp. You can get some really nice Burson discrete opamps or other such as OPA627 or OPA1612 or OPA1611 on dual adapter.

Just make sure to identify single-channel op amps and dual-channel op amps.

It looks like the 2021 Kinki models have the op amps placed very tightly together. The older Kinki EX-M1 have them spaced out more and you could possibly put in a larger Sonic Imagery or Staccato op amps.