it should have worked the way you thought it would. the trigger out is supposed to act like your built in "y" or splitter as it were. if it's not a big issue for you i'd just stick with the "y" splitter because to send it back to axiom for service means you'd have to do without it and it's nothing that's preventing the operation of your sub.
best of luck, keep us posted on whatever you decide to do or if you find a resolution to actually fix your issue.
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