Thiel Owners

Tom, with a tri amp setup, do you hear other benefits besides better matching of the amp to the driver?
Regarding amp preferences for the 3.7, it all depends how loud you want to play and how big your room is or distance from the speakers. The 3.7 is rated at 92 dB for 1 watt and pretty efficient. The stability of an amp at 2 ohm is relevant but the need to double power from 4 to 2 ohm is only meaningful if you use the maximum output. I based this on experimenting with the bryston 7bst, which allows to switch from parallel to serial, with a minimum impedance cut in half. No difference at any level below 90 dB listening level. 

^While your point has merit consider that ;  the 92db sensitivity rating is a standard rating into 8 Ohms. Drop 3 dB for each halving of impedance from there. Now we’re looking at something that is actually closer to 86 dB sensitivity. Which is why doubling down maintains frequency linearity. Jim Thiel told me himself that the power recommendations made were for standard 8 Ohm power ratings for amplifiers capable of doubling down, and if one were to use say a tube amp one should double the power recommendations as necessary. Thiel recommended 100 Watts minimum for the 3.7’s into 8 Ohms, doubling down into 2 Ohms would bring that recommendation to 400 Watts into 2 Ohms.

I really appreciate amps with clipping indicators, since there are so many variables of room, level and loudness preference - it's hard to predict amplifier power need; except that more is better, but usually at the cost of sonic finesse.

Rules - to your question of other benefits the answer is YES. I am working with older models of moderate (88dB/2.83volts range) with somewhat higher impedances (6ohm nominal). Let's say my amps are beefy enough to hear no clipping and to see little if any clip LEDs.

When using an amp for each driver, there is an unmistakable sense of ease and transparacy. Returning to the stock speaker with 1 amp imparts a hard edge, especially with loud, complex material. I love the tri-amp configuration, but that multiplies the cost of amplification.

A feasible solution would be to use amps available on the used market. A primary problem is gain-matching the amps. I am running the mids and tweeters in vertical bi-amp mode where each driver is driven by a channel of a stereo amp. Assume a matching amp for the other channel and there are no problems (after you get a splitter to send your preamp line out to both amp channels.) Now, the beefier woofer amp must be gain-matched to the smaller stereo amp. I am sending my source signal to two parallel chains, each having a preamp with volume control for manual level matching. But that's not a real world solution.
I am consulting John Siau regarding gain matching of the AHB-2 in stereo and mono. I am not certain that the levels are matched between stereo and mono. I'll report when I learn more next week. In my dreams I imagine 4 AHB-2s with each channel having a stereo amp for the mid and tweeter and a bridged mono amp for the woofer, which also controls the subwoofer.

I want to modify yesterday's statement about the deep bass performance of the AHB-2. The more I listen the more I like it, and my in-room sound pressure measurements suggest that the bass amp is weaker. Therefore my call to Benchmark regarding gain; and here's hoping they can be matched. Then, of course, funds would have to be found.

@vaankuil Aesthetix pre-power is beautiful with CS 3.7s, i have heard that combo with 3.7s.
Possible to find used.

A friend of mine drove his 3.7s with a Audio Research Ref 110 tube amp. Sounded wonderful. He decided to sell it and downsize and now the Ref 110 is driving my 2.7 with no issues at all. Best amp I have owned. The Ref 150 is supposed to have a better power supply which would have better woofer control. Whatever amp you choose look at the power supply specs. It isn’t always about the WPC.