Herb, first thing I tried was y splitter, but Apogee interface does not like signal coming from ipad, and produces static clicks / pops.
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Jim, thanks. Yep, if that mini mixer fails, switcher would be my next stop.
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Billy,
There are a few things I use on ipad.

ChordTap - older title. Has about 300 chord variations on single (!) screen. Tap to hear chords. Nice and simple.

Mapping Tonal Harmony- Mostly Jazz standards, but super fun software to learn chord movements and try your own interpretations.

Suggester - interesting chord / progression exploring software

also Yamaha Mobile Sequencer, which is essentially a grown up version of Yamaha QY100 (has all the styles from that arranger as well)