My preamp>amp balanced interconnects are 29 feet long and run into the wall, through the sill plate, under the house suspended from floor joists through loose loops of zip ties, back up through the sill plate and through the wall. One end of the cables were terminated after the wire was fished through the wall.
Very clean installation.
I recommend shielded cable to eliminate potential RFI.
Long speaker Wires.
Then, if still needed, down, thru crawl space without conduit.
Over the years, many locations, I've had very long speaker wires successfully. I've drilled holes against the walls down to my crawl space in many locations, for cable tv, coax, ethernet, signal, speakers, sub, rear surround, outdoor speakers, shop speakers. All without conduit, never an issue. Make sure you don't have mice.
Test: start with inexpensive heavy gauge lamp cord (1 strand marked). After that, you will be pleasantly surprised, then, if you must, upgrade those speaker wires in the future.
Once I made 50' long pairs out of solid core strands from electrical supply house, twisted them, they sounded as good as prior and later cables.
It's by trying stuff that you learn many 'inadvisable' solutions work well.
@tvad What did you use for for wall plates? Did you use XLR connector plates or did you have some kind of opening that allows the cables to run directly in/out of your receptacles? I’ve used XLR plates in recording studios but curious if adding 2 more connections in the signal path will degrade things. Something like this: https://www.showmecables.com/15-100-017%20ss/ I’m using 5m OCC copper cables with braided copper shielded. I could run that under the house and get another 1m on both ends to run from wall plate to components, but I assume point to point would be best? Thx for your advice!
@tvad What did you use for wall plates?
There is a photo here: https://systems.audiogon.com/systems/9072
@tvad There we go, thank you! I knew I’d seen them somewhere, albeit not at my local store. This should do the trick and hopefully not allow any mice in. Was trying to accomplish without buying new cables, so I might need to remove my XLR and Fischer terminations temporarily to fish the cables through. Thanks for the tips! Happy holiday!