The amp will work fine with the speakers. However, it's not the most sensitive speaker, which simply means that you will be somewhat limited in sound pressure levels that can be achieved.

Unless you have an unusually large room and really like to rock the joint, you probably won't use all the amp, but you will want to use the 4 ohm speaker taps.

just my 2 cents. all of these wilson and wilson type speakers try to bend the rules of physics by making a smallish box play deep bass. there is always a price to pay and it is a very low ohm spike in the bass around 80hz. usually this is in the 2-3.5 ohm range. tube amps just do not like to play at those low impedences. you should check the specs to see how low it goes or JA's measurements in the review of the sophia 2, but i do not think you will feel you have adequate bass response if you use that amp with those speakers. how do i know this?
i have a brute of a tube amp, a cary 120S good for 120 watts per side. i am using a pair of eggleston andra 2 speakers that have the characteristics i just described of low impedence in the bass. the mids and highs are excellent, the bass - disappointing. the owner of the speakers has since lent me his spectral 100w solid state amp. the result - very satisfying bass response. if possible, i would try to either get my amp to the store and hook it up or get those speakers home for a demo and try it out. i may be wrong, but this is something to be considered.
good luck, let us know what you do.

Because the Wilsons do have a 3.1 ohm minimum in the 94hz range, the 8 ohm taps will most likely have a substantial impact on the frequency response that more closely resembles their impedence plot. If the 3s are anywhere similar to the previous incarnations of Sophias, that would result in magnifying the frequencies that are easier to reproduce while shelving down the frequencies that present a more difficult load on the amp.

Wilson's own specifications suggest an amp of 25 watts minimum. ARC is a high quality amp with the ability to drive the Wilsons. To put the wattage ratings in perspective, an amp capable of producing 100 watts, all things being equal, would only net you a 3db gain in sound pressure levels.

A primary concern in this instance would be the quality of amplification and the ability to drive the Wilsons to satisfying levels in your particular room and at the sound levels that you will be listening. In this regard, my original post is pretty much unaltered.

I did a quick look at Stereophile's review of the ARC amp and JA's measurements. The reviewer mentioned that the ARC was developed using a pair of Wilson speakers.

"About that 50Wpc power rating: ARC claims that the VSi60 is designed to drive power-hungry, low-impedance speakers. In fact, Gehl told me, the amp was designed using Wilson Audio Specialties' MAXX IIs, and claims that it can drive them to satisfyingly loud levels in ARC's 32' by 28' listening room."

The review is very well flushed out and you should read it. I doubt you would have any reservations about the combination. It almost made me want to buy one.,)

http://www.stereophile.com/content/audio-research-vsi60-integrated-amplifier