I have a 2010 Mac Mini running iTunes for a large library connected to a Yamaha RXv-2700 receiver - HDMI and digital audio out from the Mac Mini. I also use a Denon DVD-2930 for CDs and DVDs. I have B & W 704s, with a centre speaker HTM7, subwoofer and B&W DS1 home theater setup. I am keen to improve my audio performance for music. Do I need an external dac (been looking at reviews of the ARCAM rDac and the M1 DAC? Should I be happy with the DAC capabilities of the Yamaha receiver? Would appreciate guidance.