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Has coiled cord. Which I don't tolerate, but others apparently do. If you have large ears they may not fit comfortably. Try before you buy.
Their sensitivity spec is also hosed - "106 dB/W/m" - albeit usable if one discerns the intent. Clearly, they are not going to produce 106 dB at one meter. Presumably that extra "/m" snuck in from loudspeaker specifications (copy/paste by someone not entirely qualified, or careless). In which case, the sensitivity spec should have read "106 dB @ 1W".
Driven with 1 Vrms (= 16 mW into 63 Ohm) you should get about 88 dB peak. Average level will depend on compression, if any, and on your technique and style.
Note that more expensive headphones may be more efficient. e.g. BeyerDynamic DT700M: 105 dB @ 0.1 W. That's 3 dB less max output @ 10 dB lower input than the Sony. Partially offset by their impedance being 80 Ohm (= 12.5 mW @ 1 Vrms).
Regardless, driving headphones with 1 Vrms max. is not optimal, which is why real headphone amps (e.g. Cafe Walter, and some of the aforementioned mixers) use a greater power supply voltage, which permits a larger output voltage.