I would consider the Analysis Plus OVal -9 and Oval -I interconnect. thats what i use with my 1.5's and Jolida 1501RC. Most "transparent' cable s i've used. Available for sale too as I am upgrading the Thiels.
I use to own the 1.5's. I cabled them with MIT 330 interconnects and MIT 750 shotgun speaker cables. If you can swing the investment I think you'll be happy. Ultimately I would go with 330 shotgun interconnects to match the speaker cables perfect. I also used an MIT reference digital cable. These cables work great with Thiel speakers. The trick is to find them for at least 50% off retail. They can be had for even less if you play your cards right.
I was using 330 shotguns and auditioned some kimber ss and kcag and with my system it really opened up, more clarity, detail, and transparancy. I am now using kcag and kctg with MIT 750+ S3 with Thiel 3.6's and the result is the best I've had and I've had this system several years. The MIT's fill up the soundstage and give the Thiels a presence and weight I haven't gotton with other cables, the transparancy of the kimbers and 3 diminisionality of the MIT's are a great combination in my system. There are no shortcuts unfortunately, trial and error is the only way to ever really be satisfied.
I'm using MH-750 HE (High Enery) speaker wire to the Thiel 1.5s, MI-330 Series 2 from the pre to the amp, and MI-330 Plus from the CDP to the pre. Total cost for the cable was $490 used. You're also missing half the sound staging capability of the Thiels without Sound Anchors stands ($325 shipped). The results are detail, transparency, and awesome sound stage. I would spring for the higher end 330/750 combos if you can but not at the expense of the stands. You will want a musical CDP. The Cary 303 should be great from what I hear. leo.