Unison Research Aria S2K with Hales Revelation 1 [bookshelf speakers]

I purchased a pair of Hales Revelation One's back in the late 90's and I've had them in storage for quite a while.  I have an opportunity to purchase a Unison Research Aria S2K tube amplifier from a friend.  Does anyone have any knowledge or opinion as to whether this would be a good mating of amp and speaker?  The amp is favorably rated, and many report that you should not be fooled by the low power output; that it drives fairly large speakers very well.  But at 15W pc, will they drive the Hales sufficiently?  The current owner of the Unison amp is driving Nola Viper Reference Loudspeakers (whatever variant was available in 2006 when he purchased them) which are rather large floor towers, and he is quite satisfied with the performance.

Anything you can contribute would be appreciated.  Thanks!