I think I found a perfect solution for what I am trying to accomplish. IK iRig2. While it's labeled as "interface", and technically it is, but unlike traditional interfaces that require certain apps, this is a pass-through device that uses ipad's phones/mic 3.5mm input to split the signal to headphones and traditional 1/4" input. My main concern using "just" cables is higher gain from Yamaha, however this box solves this as it has a passive mechanical gain dial.

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