The WA22 is only slightly less capable than the WA5, which will perform better if you want to drive two phones at once.  If you try to drive two phones with the WA22, you will experience very slight sound degradation.

I own a Woo WA22 headphone amp.  It drives an LCD-3 through a 4-ft ALO Reference 16 cable.  The WA22's original tubes have been replaced with a 7236 Sylvania matched pair, a 6SN7 Sylvania VT231 NOS Matched pair, and a 274B Sophia Princess Mesh Plate.