Try the Canare 4S11 linked above.
Two of the 15 foot runs will be around $140 from Amazon.
I used it (bulk cable) for 3 months and can recommend it.
It's s PITA to strip so go with the ready made cables.
DeKay
Need recommendations on 15ft speaker cables
Hi,
I find myself ina situation where I need around 15ft cable pair. Currently I have blue jean Rca cables running. I have upgraded all the other cables and this is the final frontier. Online it is pretty tricky to find used cables of this length.. I see transparent reference cables mostly, which I learned are custom tuned for specific gear..
Looking for suggestions from the community on options that will provide SQ upgrade in my situation through speaker cable change..