FWIW, after reading the OP I tried this with my ES-8+H90 and had the same result = no audio to tuner in using inputs 2-4.
Maybe the tuner algo *only* sees input 1?
(@dpbeason – I know you didn’t want any MIDI suggestions, but I’m going there with a handy tip… once the input issue is resolved, you can program the ‘mute’ switch on the ES-8 to flip on the H90 tuner at the same time your muting the ES-8. just a suggestion.)
