
the syl 7236 or ts5998 (if you can find them) are almost must-have upgrades. when i bought my wa2 i used this thread which really helped me see some of the options available for the other tubes.
http://www.head-fi.org/t/574969/good-tube-combinations-for-the-woo-audio-2
Between them, I'd go TS5998s (or TS7236 if you can't get the 5998s).























