So in the last few months, I've demo'ed the following tube amps with my Model 19's:
- Coincident Frankenstein monoblocks (8 wpc)... very nice sound, but not enough power to generate adequate bass
- Consonance integrated with four 300B's (approx. 18 wpc)... not enough power and overall sound was too tame
- Chinese SET integrated with 845 tubes (23 wpc)... wonderful sound quality, but ground loop hum and noise from transformers were show stoppers. I really wanted these to work as the sound quality was impressive.
- Quicksilver Mid Mono's (40 wpc)... bass was inadequate and dynamics were too tame
- Quicksilver KT Mono's with KT150 power tubes (100 wpc)... Finally, I've found amps with enough power to properly drive my 19's. I never thought I'd need amps this powerful to drive speakers with such a high efficiency rating. So far I'm about 75 hours into the break in process, but once they reached the 50 hour mark, I knew these amps were keepers. Excellent dynamics, plenty of drive and very transparent.
I initially used a Music Reference RM9 MK2 (125 wpc) with the 19's and they sounded very good... but based upon the 19's high efficiency rating, I wanted to try some lower power tube amps. Little did I know that the 19's high efficiency did not necessarily translate to being able to use low powered amps. So... based upon my experience, my takeaway is that Model 19's need some power to get them to open up. YMMV.