What kind of budget are you looking at? HD600 scale VERY well and you have a very broad range of headphones there. My CKK-III is OK with HD580, but I think that a Millet MAX is better and the PPAv2 even better. Haven't heard EC/SS so I can't comment.
im trading my Melos SHA-1 w Telefunken tubes (~$450-500) for an SS amp. so my budget is quite broad, but someone offered me the CK2III as a trade option so thats why im asking. I dont think i want to try millet since i would like to try SS amps/