Snakeoil indeed, most of it.
O.K., you could argue some justification for getting clean power with as low a source impedance as possible. If the equipment is running from a tatty old 100' 18-gauge extension cord in a loose receptacle which on the end of a undersized branch circuit which has a bad ground and fridges and A/C compressors clicking on and off, you might get some noise problems.
But beyond a sensible approach of using suitably sized cable, good connections, etc. it just gets silly. If the system already has its own dedicated sub-panel and properly sized conductors, throwing away money on nonsense like $300/ft. cable isn't going to do anything.
Remember those $150-ish "Audio grade" receptacles from a while back? I haven't heard about the PoCo's building "audio grade" power plants yet, nor "audio grade" transmission lines.
