Warren, although your question mainly relates to appropriate amplifiers, there's an underlying theme which draws a comment: why would you intentionally limit yourself to using only two speakers? If you have a multiple speaker setup now you should consider making the best use of all of them, even with two-channel source material, through the excellent ambience steering available(e.g. DPLII, Logic 7, Neo:6).

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Enjoy the music, not the equipment.