AV / Stereo setup - help!

[Run_DMH]

I recently bought a projector (Epson TW7200) and 5.1 surround speakers (Q Acoustics Q7000i) and have them running through a Marantz AV Receiver (NR1501). The receiver is capable of 7.1 surround sound and I was wondering whether buying a pair of floor stander (bi-wirable) speakers to replace my front left/right surround speakers would help me play stereo quality? Would a product like the Arcam irDAC or rDock help? My main source of music is an iPhone 6+. Appreciate any help/guidance.

 

[Run_DMH]

Am open to upgrading receiver if that is a better option.