Thiel Owners

To my knowledge, I don't know of an independent lab testing the full specs.  There's a review (without measurements) by a member of the SF Audiophile Society and he notes about its 2 ohm rating "“2 ohms stable” (not sure exactly what that means?)"

I'm also not aware of an independent lab test of my old Modwright KWA 150SE.  There's a review I saw that indicates a 4 ohm minimum impedance but there are no accompanying measurements.  My old (before the Modwright), Bryston 14BSST has some (but not much) actual measurements 2 ohm (Stereophile) but not with lots of watts and the Bryston was rated 600W into 8 ohms and 900 into 4.  I had Thiel 7.2s before the 3.7s.  The 7.2s were a harder load.  I had to build a custom amp stand with fans for the Bryston and the Modwright still got very hot but did not shut down into protection mode like the Bryston.  The Modwright got a drop less hot with the 3.7s,

So all I can tell you from real world experiences (and the room in my old house had 19 ft. ceilings and opened into other spaces) about problems or lack of driving my Thiel speakers.  When I sent inquires before and after getting the 14BSST lightly used they danced around my questions.  They also made a 20 amp version of the 14BSST (for low impedance speakers but I just had a separate (on its own breaker and receptacle) 15 amp circuit for the Bryston.  So that's should be a clue that in my situation with a huge room (probably over 7,000 cu ft) the 14BSST 15 amp version was not capable of handling the impedance.

So in the real world in my system (Modwright LS 36.5 DM preamp) all I can tell you is what sounds better (and not my opinion as I've had several other people over who agree) and drives my speakers better.  The Modwright amp would get hot enough that it would hurt touching it even though the heatsinks were inside the case.  If one goes to hifishark, there's a used Modwright listed for an asking price of $3,150 including PayPal fees and the amp is a current model that now lists for $11k.  I've noted before that audophiles, manufacturers and retailers tend to stick to conclusions about new technology (and it's not unique to audio) well past the actual performance of this newer technology.  The guy I sold my modded dual mono IcePower amp was buying it to power woofers and had also previously owned the Modwright amp and would probably have substantially similar conclusions about its sound vs. what I have (and it's in a different system in a different room).

So all I would advice anyone is to take advantage of any trial period (and break in the amp), assuming it has one and give it a try.  You might be surprised. I was shocked with my first Class D stereo IcePower amp.  A friend asked about Class D and last I heard (a few years prior) them they had gotten better but I wasn't sure if they had come of age.  I told him I'd get one and use it in a secondary system.  I broke it in using a secondary system of Ohm Microwalsh Tall speakers (augmentated by a Rel Strata III sub, a Meitner MA-1 DAC and an Odyssey Candela preamp.  I had a Bryston 3BST amp in the system.  I was in shock out of the box what a huge difference there was vs. the 3BST and even more amazed when I put it in the main system.

Keep in mind @unsound listens very loudly, peaks at 105 dB. Most Thiels are certainly going to need a boatload of power 2-4 ohms to reach that level. If I had that listening preference, I would pick different speakers.

If you listen to Thiels at more typical levels, it opens up many options. IMO, test results of steady state signals are , at best, a guide. It’s fair, I think, to look at the measurements and conclude a 10 W SET is a poor match for the CS5. But there is a wide middle-ground where you might let your ear be your guide. Here are the measurements for my amp which @unsound has informed me is a poor match for the CS2.4 despite, apparently, never having listened to the combo:

https://www.hifinews.com/content/ayre-ax-5-twenty-integrated-amplifier-lab-report

  @casecadesphil,  As you may well know as a loudspeakers impedance drops so respectively does it's sensitivity. The 400 Watts into 2 Ohms previously suggested is similar to 100 Watts into 8 Ohms. 100 Watts is the minimum Thiel recommended for the CS 2.4's. But that's at an amps standard 8 Ohm rating with the assumption that the amp is of such quality that it can double down with impedance to compensate for the actual impedance load. Amps are typically rated from 8 Ohms/ 4 Ohms / 2 Ohms and in some cases 16 Ohms, so that's what we have to work with. So with that in mind the as used minimum recommendation would be 400 Watts into 2 Ohms. If an amp can't double down from the minimum 100 Watts into 8 Ohms recommendation then the speaker is losing potential useable power. Many amps can not keep up with the power to sensitivity ratio -3dB for each halving of impedance. In which case one would need to start with more power.  In the case of these Thiels at least the impedance is fairly consistent, so the loss of frequency linearity doesn't suffer that much.

Being "stable" into a given load only means that the amp won't go into oscillation when presented with such a load. It is not a measure or power delivery, distortion or the quality of sound when presented with such a load. 

@beetlemania , those are random peaks into a load that doesn't drop below 4 Ohms. My amp is capable of 500 Watts per channel continuous into 4 Ohms and double that for up to a couple of minutes. All within Thiel's recommendation.

The “dynamic power” tests are sine-waves (or square-waves), not random. These are much closer to, you know, actual music than steady state signals. I wish Stereophile had kept that in their bag.

>>>doesn't drop below 4 Ohm
Excuse me?