The title of this FAQ is a bit misleading (on purpose). Some amplifiers use entirely different sections of the amplifier for the headphone output vs the speaker output. This is not the case with Linear Tube Audio amplifiers.
In all Linear Tube Audio amplifiers, all the outputs - headphone, speaker, and preamp outputs - use all of the same circuitry, tubes, etc. There is no separate "headphone section" in LTA amps. This means you get identical sonic flavor no matter how you choose to listen.