I plan on running the XLR balanced out of my pre-amp to the BHSE (the potential one, that is still in parts at Justin's new shop). The pre-amp has the turntable, DAC, cable box, and Oppo 95 running into it. It just seems simpler to keep the pre-amp in the loop, rather than trying to run all the sources through the BHSE first. I do tend to listen to the speakers primarily. Will see if this changes with the BHSE. I am assembling the shelves this week which will be holding the headphone amp, I will have a Bottlehead Crack with HD650s as a place holder until this batch of BHSE ships. (hmm, I will have to see if there are 2 pair of RCA outs on my pre-amp, the Crack does not do balanced.
My power amp only has RCA single ended inputs, so it already has a long pair of RCA cables from the pre-amp to it and therefore the speakers.
I plan to run some sort of input from my non-music server computer into one of the RCA pairs on the BHSE just to be able to listen to random stuff from the computer through the headphones, rather than the computer speakers. (Currently those are an AudioEngine D1 and some Bang & Olefson powered computer speakers)
Undecided about getting different tubes. I will run in the BHSE in with the stock tubes, I have a nicely broken in Quad of Sed Winged C EL34s to try before considering another set of EL34/6CA7 tubes. I have a quad of the Shugang Treasure 6CA7 tubes in my power amp, which I might try, and see whether I prefer the EL34 or the 6CA7. I know I liked the 6CA7 better in my power amp.