Intex cables are my cable of choice. Intexcables.com only because they inscribe your name on the plug
I looked at their site and find 2 disturbing things that come up regularly when troubleshooting amps for "failures" that have nothing to do with the amps themselves.
1. Unplated brass, bronze or copper, like they show on their plug's tip and sleeve will always oxidize (when I use the term oxidize, I mean chemically react with oxygen as well as with sulfates and chlorides) which can result in intermittent connections. IMO and IME, any reactive metals like the above should always be plated with hard nickle to reduce this issue. I can't tell you the number of intermittent issues we have traced back to unplated brass connectors (makes no difference which brand). ALL pro audio connectors used in the live sound, broadcast and recording industries are plated for this reason. What's kind of ironic is that the Belden 8412 cable uses plated/tinned conductor stands to improve performance of the shield as well as to improve solderability and protect the conductors from the effects of the rubber insulation (which has some mild corrosive properties). For telephone use, it's not (as much of) a problem because the voltages are high enough to punch through these oxide layers though that doesn't mean they were problem free. The voltages in common instrument and line level audio applications are nowhere near high enough voltage to accomplish this reliably.
2. 1/4" Connector tip shape does not conform to the audio industry standard. The tip shape used is from the telephone industry patch bay and differs from what has been used in the audio industry for the last 50 years. The reason for the difference is that the jacks used in the telephone industry (and some adapted for the recording industry) use a different type of contact geometry (angle of attack) and the more blunt, rounded tip can catch the leading edge of the contact wrong and fold the jack contact over or twist the contact arm (ruining the jack). This was a lot more common 30+ years ago when these plugs were repurposed by folks trying to save money as patch bay (switchboard) installations were being ripped out and these plugs were available surplus. There are reasons the name brand, main stream manufacturers design things the way they do.
Correct tip shape for audio:
Correct tip shape for telephone and some military applications (incorrect for audio):
3. Using 8412 wire with one of the two wires removed, and promoting the "coaxial" nature of the wire as a feature is obviously questionable from an amp designer's perspective. A coaxial configuration will always have a higher capacitance per foot, and that capacitance is less lossy which makes it more troublesome. Some amplifiers can become unstable and oscillate (sometimes fatally) under a capacitive load which is why many amplifier manufacturers warn against it and why many of us design specific protection circuits into our amplifiers to protect against it.
I hope this helps with the understanding behind WHY manufacturers of audio equipment recommend or recommend against using certain things.
