New to Digital

I am a novice with digital music, and would like some advice on some digital options that are not cost prohibitive.

I have a Yamaha A-S701 amp, a Yamaha 
YBA-11 Bluetooth Wireless Audio Receiver, and ADS L9e monitor speakers.

I currently just use Amazon Music from my iPhone Bluetooth. I believe that I can do better with sound quality, and am interested in your  thoughts.