Part of the problem matching amplifier to these speakers is lack of a provided impedance frequency curve from the manufacturer. As the owner has stated, it is not required but I find myself gravitating as a consumer towards manufacturers that are more forthcoming with specific component parts and measurements. For ex, Primaluna I think does a good job with this on their website. DI measurements are still lacking and At this point all we can do is hope that stereophile reviews or time tested reports make their way. Although this thread is full of anecdotal reports and at 1500 + posts, it begs for organization.
I ran a test cd, at relatively low volumes , and subjectively evaluated frequency response, using an otl tube amp that is sensitive to impedance challenges:
I found a good response from 40 hz to 10k.
Like a bell curve, 20, 30, and 11k, and 12k were barely audible
For some reason there was a significant dip at 60 Hz
and 800 through 3150 hz were the loudest frequencies
The unaccounted for variables are overwhelming But the drop at 60 is a bit puzzling. Unless I have 60 hz hearing loss among other possibilities. I wonder if anyone else has experienced this?