From their perch atop headfi's premier sponsor lounge, Woo Audio massage in the new 234 MONO headphone amp with tube switching key (TSK) tech that allows various power tubes to be switched out from the same socket. Perhaps more interesting is the fact that MONO is both a headphone amp and a speaker amp. Perhaps more interesting than that is the MONO's stunning organic design.
More details and rather fine photos at the MONO thread.
Ω was rather impressed by their recent WA7 Fireflies.