hi cheetah and welcome to ak.that is a nice setup you just bought.i dont have the au9900 but do own a ba3000 and tu9900.i currently run a pr of altec 19's with that setup.
I don't have the AU 9900 but I have the AU-D11 and they are hooked up to some Thiel CS 1.2s and Polk SDA-2As. The Polks are great for loud rock and the Thiels for most everything else.
AU-9900 running Vandy 2C's, and when I'm in the mood, stacked HPM-40's over 60's for some serious ROCK! The Vandy's aren't very high effiency, and I think may be underpowered on the 9900 though. I'd really like to hear the sansui/thiel combo though! I've heard thiel's on a linn system and they were a little 'dry' but detailed like crazy would seem like a good match with a sansui or maybe a tube setup? Have you compared them to amps other than the 9900??
sansui au417 and I run either hpm100 or polk monitor 11. The hpm/sansui does rock very well and I use this most of the time. When I used the polks I added a sub WOW I loved it but I need the sub for my 6.1 system. Tones near neutral loudness on.
at present, I'm having a shootout in the huge vaulted room between the AU-7900, and G-7500, thru Triangle Celius 202's. Upstairs, I'm getting great music From a beat-up AU-6600 resurrected back to life, thru rewired/recapped Avid 102's.
I've spent the last few months listening to a refurbished AU-11000 driving Spendor S8e's. In my medium size, but irregularly shaped room it sounds better than anything I've heard in my home.
Bryan
Sansui: AU-11000, AU-11000A, AU-9900, TU-9900, TU-9500, AU-11 II, SR-838