No doubt the Woo's are wonderful, but at a price, of course. I've found great synergy with my HD600's in a Peter Millet Mini-Max, which (if you are into DIY) can be built as a kit for about $260. Or purchased used or from various builders over at head-fi.net
Headphone amp for Sennheiser HD 600/650?
What are the most synergistic headphone amps for use with either the HD 600 or 650?