I don't think there is any reason to remotely suspect the M15 or M11Pro for instance have any technical reason to sound better than the Q5s. Any of those specifications that change with new DAC chip iterations (for example) were already so good as to be inaudible. In other words the difference between THD of 0.0025 and say 0.0125 is completely inaudible, same with SNR ratios, they have been audibly transparent for years now anyway. Saying that, I am starting to really see the appeal of a great DAP. Once we get a great DAP like an M15, but with even more power, I would be ready to buy.
The idea of everything being right there in the palm of my hand, player, amp, Bluetooth receiver/transmitter, standalone DAC, I mean why wouldn't I want that? So the fact that people find that the Q5s sounds that good is fantastic, but it also tells me that the M11Pro must sound fantastic as well. Pretty sure once I graduate from this program and I find work in my field I will be treating myself to an M15. I really respect and trust FiiO gear. I would also be interested in trying a Sony NW-ZX507, but for certain it will be lacking power that the M15 can provide.