Disagree if you must. You may be right. I've not heard either the M^3 or Woo, but outside of DIY amps, which would be the way to go if you could, what other amps under $400 new can drive K340s as well as sound decent with a range of cans, especially if you're interested in the small footprint of solid state, which I am? I also think the Heed was over-hyped, but that's a separate issue. What headphones were you using? It's not great with 650s, that's for sure, but has done decently with most everything else I've tried.
@op, enjoy your opera. If there comes a time you might want to try out something different, you will.