You can populate any of the voice family buttons with whatever voices you like. For example, the El Piano slot has a load of El Piano's (makes sense). When I push the "Voice List" button, I have 2 pages of 10 fav voices ready to play by hitting F1-F10 buttons. The procedure is on P75 of my manual but don't know about the Audya4. Look under "Voice List".
The point is that you can set up favorites any way you want. Instead of having all kinds of voices under one voice family, like I did, you can have different favorites under each button.
The reason I did it my way, is because I can have my voice list screen open and change voices with one F button, instantly.
I heard the Audya4 manual is not the best, so if you need help, holler.
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