Of the 3 the Anthem would be the best. Not sure what your objectives are, for sound quality your may gain from placebo effect. The 606 (from experience) should sound as good as any of those. Even in terms of power output the 606 will hold its own against those 3 except when all channels are driven. Even then it is a moot point as it's ACD output will not be anywhere near 3 dB lower than the NAD, HK and Anthem. So I hope your goals are well beyond sound quality and raw power.