Is there a difference between instrument cable and speaker cable (TS connectors)? The only difference I can really tell is the AWG they are made of.
Don't use instrument cables for speakers. If the amp is high power, it can arc through a thin spot in the insulation, which isn't rare since instrument cables are frequently stepped on. Instrument cable, as posted, is thin gauge wire or coaxial and speaker wire is significantly heavier with two parallel or slightly twisted conductors. If the caps unscrew, do that and look at it. If they're molded, while they may seem like a good idea, they can't be repaired on-site, which usually means the system is down until they're replaced or repaired.
