Quicksilver amps an appropriate match for Wilson Sophia?

Wilson Sophia II are 89dB and 4 Ohms.

Wilson Audio Specialties Sophia loudspeaker Specifications
Description: Three-way, floorstanding, reflex-loaded loudspeaker. Drive-units: 1" (25mm) inverted titanium-dome tweeter, 7" (178mm) paper-cone midrange unit, 10" (254mm) aluminum-cone woofer. Frequency response: 29Hz-22.5kHz, +0/-3dB. Sensitivity: 89dB/2.83V/m. Impedance: 4 ohms nominal, 3 ohms minimum. Recommended power: >12Wpc.
Dimensions: 41" (1042mm) H by 12" (305mm) W by 18" (457mm) D. Weight: 160 lbs (72.7kg) each.

Those are efficient speakers. In your size room you really don't need a big watt power amp. Since you already have the mini-mite you should get a pair of KT88's just to see if you like them better than the EL34's. If you are set on going to a bigger amp I think the mid-mono's would be fine. BTW,if you decide to try a KT88 you can get a pair of EH for under $70 at tube depot.

"Very interested in the V4, the Silver 88 or even the mid-monos. Which do you think would sound best, and why?"

The V4's would be a great choice. I still regret not buying them.

Quicksilver build quality and more importantly sound quality is excellent for the money.

On a total impulse buy, not even looking for an amp I picked up a pair of Mid Monos back in November from a fellow A-Goner close by. They are GREAT amps for the money... When I got them they had 6L6c outputs and they sounded good but after a tube went I replaced them with the original spec EL34 and they sounded even better.

When my daughter graduates I am going to buy a pair of Silver 88's. But for now I'm perfectly content with these little guys, they sound better than any 40 watt amp has a right to.