I do not believe that the above post is necessarily correct about Kimber Select being bright with Thiel and Levinson, either on their own or by comparison to Transparent.
While I have never owned Thiel, I am well aware of their reputation as being bright compared to most high-end speakers. That said, I have used all five Kimber Select interconnect models in my system at one time or another, as well as the all-copper and then all-silver Select speaker cables, all with a Levinson 360s/37 DAC/transport combination, and not found the sound to be bright in the least (my other basic upstream components: VPI Aries/JMW 10.5/v.d.H Frog analog, Rowland Coherence II preamp, VAC 140/140 Mk. III monoblock amps, and Revel Salons).
When Kimber introduced the Select interconnects, the copper model (1010) and copper/silver hybrid (1020) were thought by some to be a bit lean sounding. As a result, they doubled the number of conductors in each interconnect and reintroduced both models with new names (1011 and 1021 for the RCA models -- don't know the corresponding name for the balanced models). The all-silver model, the 1030, has always had twice the number of conductors as the 1010 and 1020, and has never been modified. One very important caveat: the "Black Pearl" silver conductor in the 1021, 1030 (and 3035 and 3038 speaker cables) takes forever to fully break in -- 1,000 hours -- so if you have dealer demos, there is a strong chance that they are not fully broken in and will sound closed-down.
I also ran the Kimber Select all-silver digital cable (XLR terminations) for two years between my 360s and 37, the sound being superlative. For whatever it's worth, customer service at Madrigal mentioned to me that they love that cable and that "there is a lot of Kimber around here".
None of these cables has ever sounded bright in my systems, and I am not aware of "brightness" being a knock on these cables more generally. The all-silver and hybrid silver/copper Select interconnect and speaker cable models can expose the grain and other problems in a system because the silver in them passes more information from the midrange on up than most copper designs, but this is the fault of mediocre upstream components, not the interconnects / speaker cables.
As for Transparent Ultra, it depends upon which level of "Ultra" you are talking about, but my best hi-fi friend dumped the top-of-the-line Ultra he had throughout his entire system for Kimber 1030. Six months later, however, he dumped all of his Kimber 1030 in favor of Jena Symphony, so this isn't much of an endorsement for Kimber, but in his system, the 1030 was superior to the Transparent Ultra. As for the Jena Symphony, it evidently works really well in a lot of systems, and many of the A-Gon "elite" have dumped Valhalla and other very high-end cables in favor of Symphony (there are numerous threads on A-Gon about this). Symphony is a bit cheaper than Kimber Select 1030 and about the same price as the top-of-the-line Transparent Ultra. A-Gon member Jtinn is a Jena dealer (Chambers Audio) and you may wish to contact him about a home trial -- I believe that is possible.
Another concern about Transparent is the network boxes. Although Transparent's very best products are well-made and sound great (they should, given the pricing), the quality of the components in the network boxes has been the source of some controversy (i.e., really cheap), and for related reasons, some people report a degradation in sound quality as the interconnects or speaker cables age.
Returning to directly address your question, however, your front-end components are all vintage Levinson, and are thus not grainy or lacking in refinement, so the signal arriving at your Thiels will not be inherently tipped up in the treble. I am thus sure that either the Transparent and Kimber Select (if silver, must be fully broken in) will not be the source of brightness and will sound really fine. Senior TAS reviewer Anthony Cordesman used both Kimber Select and Transparent Reference XL with Thiel 7.2's for several years as his reference, and loved the sound with both.
Good luck.
