When using salvage cable, you want to make line level signals go on twisted pair. So you need to cut back enough to see if any pairs are twisted. At 4 m length I've had trouble with RF pickup on ordinary RCA coax. twisted pair is quieter at that distance.
I just made a dual channel cable out of cat 6 cable with the ends cut off. Very nice. Tight twist in cat 6 cable.
Even if the conductors in this were silver, at 1000 ohms source impedance (low wattage op amp) and input impedance of 10000 ohms, I don't see any benefit. Current is too low to have much trouble with a little resistance.
If the "phono" cable goes to an actual turntable with mm or mc cartridge, those have trouble driving more than 2 m due to the capacitance. Which is why I have 4 m cables between my disco mixer & power amp, the turntable won't fit over by the power amp.
The modern setup with RIAA board built into the turntable is a great solution to this problem. Unfortunately the only turntables for sale around here are Crosley, which may be ceramic Piezo cartridge. Those in my experience wipe the highs off LP's.