I don't have the power supply yet so I can't measure the exact voltage. remember this is for fun and for me to learn and I have a good amount to learn.What does hope have to do with it?
(One pretty much knows what it will do before building it.)
The power supply determines the rail voltage and the current available determines the impedence of speakers it can push.
Why not go for 8 ohm speakers? And run higher rail voltage?
And what SPL requires 30W RMS?