Thanks for the responses guys. The earmax was definitely worth the used price I paid, and I actually liked it better - less fatiguing, smooth, natural sound - with the HD650s than other larger, more expensive tube amps I've tried at meets. The quality of the sound is quite good for this small device. Perhaps I'll upgrade to Pro when one comes up for sale.
I probably won't be getting the phenix/sense anytime soon, but it looks like an amazing deal if it even comes close to earmax sound. Anyone in the LA area who has one is welcome to compare with my original earmax!