Scoring on Used Thiels here

mapman - Your Bel Canto integrated should be fine.  It's rated at 60 watts @ 8 ohms, but double to 120 watts @ 4 ohms...always a good sign of a well-engineered amplifier.  More importantly, it's able to deliver 30 amperes of peak current, so it should be able to handle most any Thiel quite well, even the notoriously demanding 3.6's & 3.7's.

Bel Canto's amplification products typically measure much better than they rate them, so you may be well surprised at how loud you can make the Thiels play.  Again, just be mindful that the woofers, mid-bass & tweeters are handling a wider range of frequencies than usual due to the First-Order crossovers, so blowing a driver is a concern if you ever move on to something with 300+ watts.  At 120, you should be fine... 

What I've found is that, while they instantly captivate & amaze at lower & moderate listening volumes, the Thiels really "clear their throats" as you start going past 12:00 on the volume knob.  They LOVE to sing with some real volume being applied.  It sometimes becomes a bit "uncomfortable" listening this loud, but it's astonishing how easy & detailed the presentation is at these sound levels.  Amazing speakers...

My wife wasn't exactly thrilled when I moved from stand-mount monitors (Martin Logan LX-16's w/Dynamo 300 sub) to the full-range 3.5's, but she appreciated the fact that the wood & cabinetry was much more "high-end", looking more like furniture than electronic equipment. Also, as my Thiels are truly full-range, I was able to ditch the sub as well, which resulted in a much more cohesive sounding system (the Thiels seem to play lower than the ML system ever did with the sub!) One less box in the room made my wife happy.

Please keep us updated as you search for that perfect pair!

Hi,
I caught your post, because I have a possibility to get ones to restore CS 3.5.  This pair will require at least replacement of one woofer and foam surrounds. I've never been in Thiel camp, but more certain than not that I have proper electronics to push. 
Owner will accept trade and I'm planning to trade Technics SL-D3 fully auto turntable only no headshell, dust cover or cartridge in full operational automatic condition. The turntable like that probably has value of $89max, but certainly was picked up by me from estate junk to restore.

How much bass can the room handle?

C5i doubles down to 4 ohms according to specs. I don’t see a problem there. It does well with my Dynaudio Contour 1.3mkii monitors which are likely in same class as Thiel in terms of amps needed for best results. SPL is somewhat limited I would say.

I am open to any model though the less obtrusive physically the better.  WAF matters in that room. 

Thiel appeals to me.  The low efficiency is a concern for me.

The efficiency is about average, actually. Most models rated 87-89 dB. The "problem" is the low impedance. Thiels draw a lot of current. You will want a high quality amp with a decent 4 ohm rating.

Years ago I drove a pair of CS1.6s with an Ayre AX-7e. That amp is rated at "only" 60 W but doubles into a 4 ohm load. That amp had plenty of balls to drive the Thiels as loudly as I wanted.

The amp quality part is very important. Thiels are highly resolving and will reveal weaknesses in your amp, cables, and sources. I'd MUCH rather have a high quality 60 W amp (again, with a 4 ohm rating) than a 200 W meh amp. BTW, a zero-feedback design sounds fantastic with Thiels, IME.

What Thiel models are you considering?

Was an owner of the CS 1.5, 2.2 and 2.3 but the 2.2 were my all time favorite and listening to piano music from another room sounded unbelievably real; newer drivers were not my cup of tea.

Wig

Enough for many, but perhaps not ideal.

I have been pondering some different speakers in my second system.  

Amp is 60w/ch Bel Canto c5i.   Current speakers in there are 90db efficient Triangle Titus XS and a sub.  

These sound great but am interested in trying something different and bigger.  Waf is a factor.  

Thiel appeals to me.  The low efficiency is a concern for me.   Its a large family room kitchen area.  I do not need to go uber loud in there but do like modest volume levels when I can.   Most of the time things are not played loud in there.   I go down to my main rig for that.  

Klipsch Heresy III has been a leading contender.   I have heard and liked these and the higher efficiency is a plus.  

I've used OHM Dynaudio and the Triangle speakers with the c5i and they all sound wonderful ( but different).  

c5i is very airy and detailed with no edge ever.   I feel like most any speaker could work well with it save for volume limits with only 60w/ch.  

is that enough for any particular model Thiel?      

Thiels have always had fairly poor resale value.  It's a testament to the bad taste of an awful lot of audiophiles.  I got a used pair of 2 2s 7 or 8 years ago and they were a revelation.  For a small amount of money I got some fantastic sounding speakers that do nothing wrong.  They were laughably better than anything I'd ever heard around the price.  It took me a while to admit it but when it comes to enjoying listening to music they were better than the B&W N802s I had at the time.  I traded the B&Ws in for Thiel 3.7s and haven't looked back.  

Have to agree with beetle: With the opening of Rob’s Coherent Source Service, legacy Thiel speakers now have a brand new lease on life. Rob is from the days of the original Thiel company & has been servicing/restoring Thiels for years. Since Thiel (in this latest iteration) went kaput, he was able to acquire all the assets to the service part of the business. He has a stockpile of parts, crossovers & drivers that will allow him to pretty much rebuild any model. He is also offering cabinet re-finishing services, which, if you have ever seen a pair of Thiels, is awesome because the cabinetry on them is not only integral to the coherent source design, but in a class way above the price point even when new.

As always when looking at pre-owned equipment, buy the best conditioned pair you can afford. Cabinets are real-wood, so scratches & scrapes can easily be addressed; a good cleaning & polishing will make the wood shine! Drivers are very unique to Thiels...Jim Thiel designed them all himself & in later models, they were completely sourced & built in-house. More importantly, crossovers are First-Order (meaning the drivers handle a wider range of frequencies), so make sure the previous owner(s) didn’t blow out a driver & end up replacing it with something from some catalog. Having said that, if they were treated with care, Thiel’s build-quality & engineering resulted in very robust speaker designs...they are heavy & very well-built. Shipping usually costs a fortune.

I have a set of CS 3.5’s that I bought locally from a vintage stereo dealer this past November. I am only the second owner. Even with their age, the Thiels have been such a revelation, have been such a joy to listen to, that I’ve decided to make them the focal point of my system with regards to components & upgrades. They are ruthlessly revealing of poorly recorded material & poorly engineered components. But, if you have the goods & the high-quality amplification they require (Thiels love watts & especially, lots of current), you will not find better without spending hundreds or thousands more. In the last three months, I’ve swapped out most of my gear for Audio Research seperates (amp, line stage & phono pre-amp), all in effort to make the Thiels sing that much better. Even with all this, I have not once considered "upgrading" from my 3.5’s...the Thiels sound that good.

Good luck in your search...Enjoy the music!

Arvin

Tons of great info on "Thiel owner’s thread".

I bought a pair of CS2.4SEs just a few weeks ago knowing that Thiel was in serious trouble. I figured I’d be OK as long as the drivers were in good shape (they are flawless). Short of abuse, drivers usually last many, many years without issue. I figured I’d buy a broken pair for parts in a worst-case scenario. Capacitors can wear out over time but these can be replaced without much issue. In fact, it’s a good chance to upgrade to better sounding capacitors.

Meanwhile, Rob Gillum has just opened "Coherent Source Service" and says he has the parts and abilities to repair or replace almost anything on a Thiel. In fact, he’s even willing to honor warranty repairs for speakers still under coverage despite that he has no obligation whatsoever. Most exciting for me is he is planning "hot-rod" kits for owners to upgrade the passive pasts to maximize SQ.

I’ve listened to a wide range of speakers over the years and I’m unaware of anything <$10K than sounds better than my Thiels. Upgrading the crossovers should put me on par with most anything up to $20-30K.

To summarize, I'm a recent - enthusiastic -buyer. Zero regrets!