Thiel Owners

sdl4 - you are correct about bridged amps 'seeing' half the load impedance of a stereo amp. That said, the 2.2 is a fairly benign load, especially as Thiels go.

I recommend you compare your PS to the AHB if you can. I was gobsmacked by the difference between my S300 and the AHB. I'll soon have more to report, I'm expecting delivery today of a BM DAC3B and HPA4 front end. Better than Christmas.

I also have some thoughts about the 'extra' load imposed by the EQ - more on that later.

@sdl4, If I may, yes, bridged stereo amps typically don't handle lower impedances well. They are better suited for insensitive, high impedance speakers, where the extra power can be better appreciated, with the added benefit of better stereo separation, though typically with higher distortion levels.

 Yes, the CS 3.5's eq makes greater demands on the amp. But.... this is mitigated by cleverly using the impedance peak that typically naturally occurs due to box resonance.

Thiel CS3.5 loudspeaker Measurements | Stereophile.com 

Compare fig. 1 with fig 3. (you can ignore fig. 2 as those measurements would be specific to the testers individual room). Jim Thiel with his uncanny cleverness has the eq nearly identically overlap the impedance hump with the eq boost. This not only relieves the amp of power draw, but it also mitigates the draw from sucking power from the closely overlapping 1st order midrange. Converting a deviance from linearity into an advantage. All towards full range extended bass from a relatively small footprint, with superior time and phase coherence. Brilliant! 

Full range Class D has not traditionally worked best with low impedance loads, Specialized Class D subwoofer amps are different. Though these Class D sub amps are reputed to be the most failure prone components in the field. Parts and repairs are not especially likely to be counted upon either. On the other hand there is a new generation of Class D amp modules just coming to market that hold special promise. I'm eagerly waiting for consumer reports on these new amplifiers.

Ha, must have been typing as @TomThiel was posting.

big_greg et al,

On the 3.6s I’ve replaced the mids with rebuilts by Rob at CSS and also changed out the ferrofluid on the tweeters. The updates resulted in a very extremely small softening on the highs, but only perceptible and barely so on a few tunes. This was all done prior to auditioning the previously mentioned DACs.

@tomthiel, thanks for the additional info! I hope you enjoy your new Benchmark gear. I'll look forward to your more detailed comments on the extra load of the EQ for the CS3.5, especially with respect to what @unsound mentioned about dealing with the impedance "bump" in the low bass.

@unsound, thanks for the discussion of the comparison between Figure 1 and Figure 3 in the Stereophile article on the CS3.5. Does the impedance rise vs. the EQ boost in the low bass fully offset the extra demands for more power when the EQ is used? If an amp puts out only 100 w/channel into 8 ohms, wouldn't available power drop even lower when the impedance goes above 8 ohms?