Good stereo setup for an A body?

Would I be able to stream an app like Spotify to the DSP? (that's where all my music comes from)

How does that work?

How many channel DSP would I need?

Sorry for all the questions!
As mentioned above, any streaming app that goes out via Bluetooth will work. Look on-line for all the DSP's available. Places like Woofers etc and others will have amplified and non-amplified DSP's. Each speaker will have it's own channel, and others you can bridge the amp outputs to feed more power to , say a woofer in the trunk etc. The other nice thing about DSP's is that you can electronically cross over your speakers and use Time Delay to tune the sound.