I am using my Piano M1/Virtue One to power several balanced headphones: AKG K1000, K501, K340, Sony SA-5000. When not using the Piano, I stream music to the Virtue One through my Squeezebox via my magiDAC.
I will soon be replacing my Virtue One Classic with a new Virtue 2.2 with battery power.
This combination of components has proven to be a stunning balanced headphone driving source.
Ron