Thiel CS 3.7 and Vandersteen 5a, 5a Carbon

If you're enjoying the 3.6's in your current system, I wouldn't look at Vandersteens. Both are outstanding speakers but at two different sides of the spectrum; Vandersteens tends to be slightly dark and Thiels slightly bright, neither to the extreme. I would think that you probably have a system that tends to balance the Thiels, which means that with the Vandersteens everything will be too dark.

Thiel 3.7 is a major step up from the 3.6's.

I own both Thiel CS6 and CS2.4 as I am a huge Thiel fan, and I have listened extensively to the 5a. If I had the bux I would go with the Vandersteen simply because the bass alone is unparalleled and I do not find these speakers to be dark. They are simply amazing.

I disagree that moving from Thiel to Vandersteen will mean "everything will be too dark". I had Thiel 1.6s. I really liked them alot but wanted more bass as they pretty much didn't have any energy below 50 Hz. I considered Thiel 2.4s but decided to go with the Vandersteen 2Ce Sig IIs. IMO, the Vandersteens are better in most ways, with a full, musical sound the Thiels couldn't match albeit the Thiels wer more transparent and, maybe, a smidge more dynamic.

I've never heard the 5s but have heard the Sevens, Quatros, and Thiel 3.7. These were all in different systems/rooms, so I will not offer comparisons. They all are great speakers, however, and there is no way to make a mistake with these choices. The Sevens are a top three all time speaker in my experience. If I could afford the closely-related 5A Carbons, I would get those. I think that Vandersteens, on balance, are a "better", more musical speaker than Thiels. That said, the 3.7 is a great speaker (that also looks much nicer than any Vandersteen) that I could happily live with.

I think the 3.7 bass response is just not over emphasised and with an upgrade to Electrocompaniet Nemos (1200W into 4ohms), I thought it really came alive. I don't think it's power per se (my last amp was a 1000W into 4ohms Bel Canto REF1000M).

Anyway, I went with dual SmartSub2s to match the 3.7s which extend the bass further down to 15/20Hz.

Hmmmm,
It's odd that the THIEL/Vandersteen debate still goes on...some 30 years after I opened my Audio Store in Louisville.
Since we all 'hear' so differently its not surprising that one man's 'dark' is another's smooth, or that one man's bright, is another's 'detailed'...which brings me to a well timed 'rant'.
There IS NO right here, except for the buyer...the actual owner in each individual instance, which is why the audition is so critical in the purchase of audio goods.
A sadly, missing link in the whole process of High End Audio these days.
With the decline of Brick and Mortar stores, those evenings or weekends behind closed doors in which a guy and his wife (significant other) could take his and her fav music into a store and listen for a couple of hours in order to make his/her conclusions on which is actually 'right'. And, once again, as we all hear differently, beauty or in this instance, 'accuracy' is in the eye of the beholder. With that important part of buying now in very low availability, what to do.
Back in the day (moan, here he goes with a 'story')...audiophiles would travel on a week end to my store from up to 400 (sometimes more) miles away to make a day of listening to products, to make such a decision.
As the owner of the store I simply tried to add logic and reason to the festivities...because back then (because of corporate competitiveness) almost NOBODY had both speakers in their store...that being THIEL and Vandy.
And to me, frankly the differences are legion...
Auditioning both in a close enough time frame is critical to this decision making process.
Keep this in mind...anything that bothers you, or is an even 'slight' issue, becomes a MAJOR ISSUE over days/weeks/months.
Example, if you hear the THIEL as a bit bright, it'll make you nuts in a couple of weeks...on the other hand a touch of darkness in the Vandy will make you totally crazy with, 'what's missing here, no air'....yada, yada.

My advice...what we give you is a bit helpful, but only YOU can pick the right one...
Are they different from one another?
You betcha...(Sarah)
Night and Day and I ain't singin' Cole Porter.

Larry