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I assume the front jack has failed?

Maybe. This can be anything from a path problem to a motherboard failure.

Since you have found a workaround, I recommend declaring victory and moving on. Otherwise, it is possible to spend a lot of hours and money chasing that rabbit down the hole.

I agree with the recommendations to use an interface instead


BIAB 2025 Audiophile Mac
24Core/60CoreGPU M2 MacStudioUltra/8TB/192GB Sequoia, M1 MBAir, 2012 MBP
Digital Performer11, LogicPro, Finale27/Dorico/Encore/SmartScorePro64/Notion6 /Overture5