Thiel Owners

The 2.8 minimum impedance are manufacturer specs.  There have been independent measurements (e.g.  https://www.stereophile.com/content/thiel-cs37-loudspeaker-measurements) indicating it is either 2.4 or 2.3.  I've had different amps on my 3.7s including a Bryston 4BSST, 14BSST, Modwright KWA 150SE and the last two have been Class D (using a Ric Schultz EVS 1200 now).  When my friend worked at a hifi shop many moons ago, I helped deliver a bunch of things and often Thiel was paired with Levinson (when I had my 7.2s I had a Proceed HPA).  Like anything else it is dependent one's room and listening habits (music preferences and loudness level).  My main room in the old place (I started with 2.3s, then 7.2s and then 3.7s) was huge (something like 7,000 cubic feet that opened into other spaces and when I had an old Bryston 4BST (not the SST), I actually drove it into momentary clipping.  The 14BSST (15 amp version) could not handle the impedance (would go into thermal shutdown during music or movies which where somewhat intense) and I ended up building a custom amp stand with fans (which solved the issue).  The 3BSST wasn't as bad a load but would get the 14BSST heat sinks hot enough to burn one's hand.  The Modwright amp ran a hair cooler (and the heatsinks where inside the case).  The room in the new place is big but not as big as the old place and the Modwright did a bit better but not as well as either of the Class Ds I've used (which bested it in every way and it still shocks me to touch the amp case and hardly feel anything warmth.

tmsdrg - I am one of the culprits of touting the necessity to double power with halving impedance. My point was more academic than of real consequencel. If an amp doesn't double its power into half impedance, then it is by definition current limited. BUT, as has been pointed out here previously, that point of art is of no real importance as long as there is enough current to deliver to the load. So, doubling is not a technical necessity to drive Thiels, but that sense of anemic bass, slow transients, etc. is symptomatic of running out of current capacity. The 3.7 is about twice the efficiency as many previous Thiels, so the problem becomes less of an issue than before.

tmsrdg
In addition to the 8/4 ohm double power ratio, I find it interesting to ask a manufacturer about peak current in  (A)mperes  rating as well.
Happy Listening!

Happy Friday! All

tomthiel
As I started my higher end education back in the early 1990's via Stereophile and TAS subscriptions, I recall, Slew Rate being discussed quite often by the reviewers. In 2020, is this factor relevant as it pertains to power amplifiers?  I will concur with the CS 3.7 being very efficient, as well as, models CS 2.4, 2.4SE and 2.7.
Happy Listening!