One evening in a concert hall in England. Moral - You never get a second chance to make a first impression. Guitar leads . The braiding needs to be tight and the internal insulation good enough to prevent high signals leaking away to ground.
Speaker leads .
You can dramatically increase the performance of your set up by investing in heavy-duty speaker cables. Replace it and while you're at it replace the internal speaker cable with heavy-duty speaker wire, available at your local hi fi shop. Generally I replace standard jack sockets with stereo sockets which have an extra sprung connector which I use for earth. For plugs I avoid brass which tarnishes and does not make as good a contact as chrome or gold. Check all the sockets in your set up every six months for wear and tarnish.