The Warwick Acoustics Aperio is an electrostatic headphone. It does not connect to a normal headphone output at all — it needs a dedicated energiser that supplies a high bias voltage, so every power figure on the rest of this site is irrelevant to it. No dongle, amplifier or player will drive it, whatever its wattage.
That is the whole answer, and it is worth stating plainly because "how many milliwatts do I need" is the wrong question here. What you need is a matching energiser from the same ecosystem.
Electrostatic specifications are quoted differently and are not comparable to dynamic or planar headphones. They are listed here only so the database is complete.
200Ω · 96.0 dB/mW · Moderate
See requirements →60Ω · 90.0 dB/mW · Moderate
See requirements →200Ω · 97.0 dB/mW · Moderate
See requirements →Or open the comparison tool to put any two models side by side, or browse all 316.