The P20 drives Hifiman HE6se v2 extremely well. Some people use a speaker amp for the HE6se, whose specs include:

Frequency response: 8Hz - 65KHz
Impedance: 50 Ohms
Sensitivity: 83.5dB

This little amp was worth the initial aggravation. I’ll try to link to my suffer thread from my first week in The Ocean. It’s my most satisfying setup, and by far my cheapest. I really like the sound that enough power can deliver from planars.

Couchside at the Bravo Beach:

ALAC files
iPad, iPods and iPhones

Morrow Ultra Reference M 3.5 mini patch cable (48 SSI wires)

Or: Arcam rDock to Morrow RCA interconnects (8 SSI wires)

Bravo Ocean
Sylvania JAN 6189w 12AU7 tube

Sendy Audio stock braided cable
Youkamoo 1/4” to 4.4 TRRRS adapter

Sendy Audio Aiva planar magnetics