Hi gentlemen. I have a question about the M15, did you notice any deterioration in sound quality during longer listening sessions? for me, when the player heats up more, the sound starts to sibilize a little, I turn off the DAP for 10 minutes and everything returns to normal until it warms up more. In general, I noticed that the equipment started to heat up more than before, when I turn on the "All to DSD" function, I have to put it down while listening because it becomes uncomfortable to hold in my hand, earlier the equipment was also warming up but not as much as now.