Have thiel 3.6's. Will mcintosh ma6600 work?

At least Thiel still offers rebuilds, and I'm comforted to know that they'll be in the hands of the mfr. I agree with $600 being somewhat extravagant for the pair, but I suspect they might have been over-driven by the previous owner occasionally so...
From what I've seen on here and other sites used Thiels generally fail to sell at first, even at bargain prices. One can argue that my $850 plus the forthcoming rebuild + $600 is an iffy expenditure, but within my budget I have yet to hear something as good as these. i've seen their cs 5 on here for less than $3k....tempting!

^I completely agree!
I've been tempted too, but then I remember the cost of amplifying those 5's!

I have given in to the temptation of a well priced CS5, but fortunately had already purchased a Krell FPB 300, which powers them nicely! Thiel at one time had a pair of CS5i's with an FPB 600 in their factory showroom, so I will most likely move up to a 600 when the time is right. Krell all the way for Thiels. My 2.4's competely opened up with the FPB 300..

^Nice!

Ii don't believe anyone has mentioned this.
The Mac's power is rated into 4 ohms, not really an industry standard. Most are rated into 8 ohms. So, the impedance of the 3.6's drops below 2 ohms as I recall, though it's been years since I have recalled this.
I would NOT use a Mac. Go for an amp that truly doubles into 4 ohms. An amp that's smooth in the upper and has loads of current. As the resistance drops, the current needs go up quickly.
Research and call some THIEL Dealers. They'll be very helpful!