Have thiel 3.6's. Will mcintosh ma6600 work?

Disappoint? Not compared to an Adcom they won't.

"The Amps are 200wpc, so concerned that the wattage won't give me the detail and sound I have waited all these years to hear. Will these macs disappoint the requirements of this needy speaker?"

There's really no industry wide rules on how to rate an amplifier's power. If you took 5 or 10 amps from different companies rated for the same power, it would be unlikely to find even 2 that put out the same exact amount. McIntosh is one of the better ones when it comes to power ratings. You should have no problem driving your 3.6's. The only real issue is if you like how the McIntosh sounds. Some do, and some don't.

The Mac's with their autoformers won't double down into the 3.6's rather challenging load. Not what I would recommend.

I use to have the 3.6's great speaker but hard to drive. They can be in your face a little through the mids and highs, and they need a amp with good tight controled bass.

They do remain mostly under 3ohms, so an amp with good current is a must. Stereophile test measurements here
[url]http://www.stereophile.com/content/thiel-cs36-loudspeaker-measurements[/url]

My self I would look at amps that have reputation for good bass control, but ones with high class A bias to keep the mids and highs sweet. So the hot running medium to large size Krell's, Mark Levinson's and other manufacturers like them would be my choice for these speakers.

Read the full review here, if the 225watt VTL's couldn't do it in the bass, then I doubt the Mac's with transformer output will either.
[url]http://www.stereophile.com/floorloudspeakers/225/[/url]

Cheers George