as many piezos as speaker as possible

Hey there,

I need some help with making some decisions for a little project i like to do.

I like to use as many piezos as possible (10 to 50) as kind of speakers for low quality sinus style sounds.
I know arduino has quite limited audio playing capabilities but I dont need good quality so maybe PWM is enough.

My main goal is to play different oscillators on every different piezo in a frequency range from about 5000hz to 15000hz.

Do you think I can use shift register circuit for this?
Or is it better to build small oscillators with op amps for my needs?
Sorry, for asking so dumb. I am a bit lost.

Do they really need to be separately driven?

Would creating one really high quality signal with 10-50 synthesized sine waves, which you amplify and run to all the transducers fit your needs?