The difference is certaintly not very big as it is not so big with the m7 fed by high-quality i2s transport. The cheap r2r offerings by audio-gd seem even more advantageous in their respective price categories. The sound quality per dollar spent prize goes out to the r2r 11. I have it with akg553s at the office and am so totally satisfied with it. This is real gem. True hfi for 500$, headphones included.