Using the monitor output my PA Mixer, Yamaha EMX66M, to a Sterling S104H headphone amp via a TRS cable, I am only getting sound in one ear. The mixer is mono, so I assume the monitor out isn't capable of a dual-mono - or maybe my cables were just messed up (need to toy some more). Assuming this behavior is expected because it is a mono output, how can I rectify this?

  • Are you sure your mixer isn't stereo? It seems to have two graphic EQs (maked GEQ) on the front and two 'Master' knobs. Which output are you connecting to? Commented Jan 2, 2018 at 16:06
  • manualowl.com/m/Yamaha/EMX66M/Manual/153058 mono output needs mono jack & mono receiver or bridge. a TRS will feed only one side of a stereo amp.
    – Tetsujin
    Commented Jan 2, 2018 at 16:22
  • @Tetsujin - worth posting that as an answer, I reckon
    – Rory Alsop
    Commented Jan 2, 2018 at 17:55
  • @RoryAlsop - had a quick attempt, not seeing any easy 'amazon' type links for a quick adaptor solution... maybe my terminology doesn't match 'consumer', but idk what else to call a bridge to mono ;)
    – Tetsujin
    Commented Jan 2, 2018 at 18:04

1 Answer 1


It's a mono output jack, so needs a mono jack, or preferably TRS with bridge, if you're going to a stereo headphone amp.

A regular TRS > TRS will arrive at the headphone amp as one side of a 'stereo' feed, so will need bridging to provide dual mono. You can buy jack converters that will do this, or with a soldering iron, connect left & right, leaving ground as is.

Ref: https://www.manualowl.com/m/Yamaha/EMX66M/Manual/153058

Additional ref - Stereo and mono cables and jacks? What happens when you cross them?

  • Great, that's what I was thinking. Would you mind linking such a bridge product? I am unfamiliar and don't want to buy the wrong thing haha. Commented Jan 2, 2018 at 18:51
  • I'd really be tempted to say, go to your local Maplins/Radio Shack & tell them what you need. Googling 'stereo to mono jack' doesn't guarantee it will bridge properly. Your headphone amp will have a true stereo TRS socket & I'm not certain it will bridge correctly if you insert a regular mono jack; I'm betting it would connect Right to Ground, not Left to Right.
    – Tetsujin
    Commented Jan 2, 2018 at 18:59

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