looking for upgrade suggestions - 12,000 to spend

Chris, listen to Sdcampbell, his reply to your question is excellent. Your existing system is so good that your budget of $12k spent on speakers or source components is not sufficient to take your system to a higher level. Sure, some of the speakers you mentioned will be an improvement over the SC-IVs, but the differences are not in keeping with the cost it will take to make the change. Large dollars spent for a small sound improvement. A DSP room EQ will substantially improve your system.

If you decide to go with the TACT or its equivalent, then I would also recommend you upgrade and add the Dunlavy subwoofers. Somewhat paradoxically, the added headroom in the bass pays big benefits throughout the frequency. spectrum.

I agree with Sdcampbell and Onhwy61. The speaker room interface is of paramount importance, and optimizing it will likely yield greater significant sonic improvements than any kind of component upgrade would. You already have a very nice system.

I've also become a big believer in a high quality dedicated AC system to include excellent receptacles and good power cords that suit your taste. Good Luck, and Cheers. Craig.

So the analogue bug hasn't bitten you, eh!? For 12K, you can buy a first class analogue rig and really get the best sound from your already world-class gear.

Here's my suggestion:

Eurolab Premiere: $2100
Morch DP-6: 2300
Shelter 901: 1500
Krell KPE Reference: 2200

Note: Prices are approximate.

Good luck,
Aisip

Chris, I would say upgrade by adding a turntable to your system. 12,000 smackers could get you a great turntable and LOTS of records. This is, of course, just my opinion.

Please listen to Professor Campbell! Oh, and raise the ceiling to 10'. (That should finish off the funds.)