Not so sure what you mean, maybe shielded cable? I`d build it close to the input pot, just a few cm of wire. Tube socket can be PTFE material or so + tube shield... I posted this schematic in hope that some discussion can be made... at the end, maybe someone actually build it and try it... I hope that direct coupling between the stages have more advantages then flaws... then cathode decoupling cap C3 (220uF/160V-probably electrolitic) hasn`t large negative impact on sound (can be avoid with active load and Mu-out), etc.