I have simple mechanical 4-port switch connecting all sources and the tube pre-amp. So no need to play w/ cables.
"Duttek 4-Port AV Switch RCA Switcher 4 In 1 Out"
https://www.amazon.ca/gp/product/B077X4W4W6/ref=ppx_yo_dt_b_asin_title_o00__o00_s00?ie=UTF8&psc=1
That is:
Sources (DAC out, CD player, Tuner, Piano keyboard) --> 4-port switch —> 6J1 preamp —> power amp
Very nice. And ‘piano keyboard’ is one of your inputs? Sounds like fun.