Recommended max. length of 3.5mm cable?

Is there a good rule of thumb for the maximum length of 3.5mm cable? I notice that some of the high-end cable makers have 15-foot lengths for sale, while they may only go up to 6 feet for USB cables. I need to use a 12-foot cable if possible, but I don't want to sacrifice audio quality. Thanks.

 

Most 3.5mm cables are used to connect a headphone outlet of a smartphone to the analog input of an integrated amplifier or preamp, so that you can play your music off of your smartphone or player.

This is not a typical line level interconnect cable.

I have a long one, so that if I have guests over, they can plug their smartphones into my system and listen to how their music sounds, when played through a quality audio system and played through regular speakers.

It can be almost any length that you want it to be, 10', 15', 20' 25'.

It has a high level signal playing through it, so the actual length does not really matter.

 

Thank you! That's what I wanted to know.