Hi, I'm Nathan.Sorry to hear that you're having trouble with this but I'll do my best to help you.
What input are you using for z2?are they driven by the yamaha, or do you have an external amp, switch box, volume control, etc between the yamaha and the patio speakers?
Yes I was waiting for you to provide the requested details above:
Do you need more help with this?
If so, simply reply back on this page.
Please note: You have already paid your fee to the site; I'd like to help you and provide value for that fee, but I do need to communicate with you here to do so.