111 dB is very loud, and very bad for your hearing.
Because of varying dynamic range you can subtract about 12-6 dB from max output. Most compressed pop music is around -6dB on average, whilst jazz or classical, would probably go like -12 dB from what i have heard.
So half the volume would probably be more suitable, and even too loud since the fiio should be putting out 3/4 volts (not 100% sure, but my result is likely to be correct, i can explain if you want). This corresponds to 2.25 mW, which in term, corresponds to about 98 dB, more or less. Subtract, say 10 dB due to varying dynamic range, and you end up on 88 dB, which is on the edge of risking hearing loss, but somewhat safe.
Still, this should affect your listening experience in a negative way, since the highs and lows can get drowned out due to the eardrum tensing as a mechanism of protecting the hearing.