unsound - thanks for the input. What may not be self-evident is that changes such as these wire lengths require system tweaking. I had presumed that the system would be optimized around some fairly short umbilical length, but am open to reconsidering: perhaps a short and long version such as 1/2 and 1-1/2 meters.
Of general interest may be how Thiel approached this tweaking problem. We assumed user preference for amps and cables. Voicing and final adjustments consumed months of iterative listening tests. The (sometimes maddeningly) long delays between projected new product introductions and actual roll-out included this micro-voicing to levels considerably beyond measurement. Add to that the unannounced XO revisions during a product's life for further refinements. These micro-voicings take internal wire lengths into consideration along with the myriad other variables and interactions.Outboard XOs extend the complex cable contributions from a few feet to many feet. An additional system variable.
I'm glad you brought up this issue - I'll add it to the list of considerations.