Thiel CS3.6

Does the VT100 MKII have a 4 ohm tap? Normally many Thiel speakers love solid state amps.

The CS3.6's impedance magnitude and phase plot (fig.1) reveals a very low impedance value. The loudspeaker is under 3 ohms through most of the range, dropping to a minimum of 2.3 ohms at 3.6kHz (the cursor position). The low impedance value explains the CS3.6's need for the iron-fisted Mark Levinson No.23.5 to provide control in the bass; the CS3.6 would appear to be current-hungry.

from Stereophile's measurement section (review linked below).

At 86dB with a minima of 2.5ohm on the impedance curve and staying below 3 ohm between 100Hz and looks like 10KHz, I would not pair it up with the ARC VT100. I would look for an easier load than the Thiel 3.6. Normally however, I would tell you to choose the speaker you like first and work your way backwards and get the appropriate amp to drive it. So if the Thiel 3.6s are doing it for you, than you may want to sell the ARC VT100 and get yourself a nice SS amp that has some oomph to it and that doubles its power as the impedance is halved. My 2c worth.

ooops - forgot the link to the Stereophile review. Here you go: http://www.stereophile.com/floorloudspeakers/225/index.html

In fact there are quite a few Mark Levinson 23s (referred to in the review) on Agon right now for sale in the $1700-$2200 range. Good luck

Jab, Thiel seems to disagree with you:
http://www.thielaudio.com/THIEL_Site05/PDF_files/PDF_tech_papers/techpaper_cs6.pdf

Here it is linked up: http://www.thielaudio.com/THIEL_Site05/PDF_files/PDF_tech_papers/techpaper_cs6.pdf

My Thiels sounded like crap until I finlly bought a Threshold SA3. Only 50 watts but high current and smooth. Lovely combo. One of the stupidest things I've done in audio was to sell this amp when I sold my speakers because my new speakers needed more power, lots more. I've never used tube amps with Thiels but I did use a tube pre-amp in combo with the Threshold. Sounded pretty good!

Jab, I tried Adcom and Perreauxs - my ears still hurt! :-)

It'd be fun to hear a high watt/high current ss amp on my 3.6s, but I've been using a pair of Quicksilver 90 watt monos for a while. Maybe a tad loose on the bottom end on some recordings, but overall quite nice sounding. Good luck.

If the amp is comfortable at 2 ohms and the room is not too large, it should work fine. The Thiels crave current drive, not necessarily high wattage. If they don't get the current they need, they will sound bright and thin. Also, you should have 3 feet or more open to the sides and shouldn't sit closer than 8 feet from them.
If you give them those things, they are a delight, and one of the biggest bargains in used gear.

I have owned a pair of 3.6 since I bought them new in 1995.

IMO, they need a beefy SS amp to get them going. When I originally drove them with a Hafler 550 (255wpc) amp, I could not make them sing. Don't get me wrong, the sound was nice, but if you want them to sound their best, a powerful amp is a must.

Newbee, you should have heard those Thiels with a bigger Threshold! What tube pre did you use with the Threshold/Thiels?

Unsound, I used (and still do) an ARC SP10II. It was revelatory in its hey day. I wasn't so wild about the matching D115II though. Phono stage is still pretty good. And if I ever find some mint SA 1's I'll buy them just for the nostalgia effect if nothing else. :-)

BTW, I'm assuming you are familiar with Thresholds 'optical bias' which was introduced after the initial production of the SA series. Did you find it added to the sound, quality wise? I never heard it but the feedback I got was that it sort of brighten them up a bit.

I hope the OP won't mind this?
Newbee, I haven't compared non-optical bias with an optical bias units. I've been told by someone I trust in these matters that the optical-bias helped a great deal with maintaining the bias and even more with overall reliability.