Quicksilver amps an appropriate match for Wilson Sophia?

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.

I don't expect that the entire line of QS monoblocks are essentially the same, save for increasing power, correct?

What are the specific sound qualities that improve as power is increased (other than volume)?

I think I've ruled out the mid-monos. All things considered, I don't expect they'd be significantly different than the mini mites. For slight changes, I can simply engage in tube swapping with my mini-mites.

Can anyone make a comparison between the VTL ST150 and the QS V4?

Also, still hoping to hear from someone who has matched QS monoblocks with Wilson Sophia loudspeakers.

Allison2,
just expressing some thoughts here - I don't know if the QS amps are suited to the Wilson speakers or not. I've not seen this pairing often but it does not mean that it won't work.

In power amps, the bass heft is, I believe, directly proportional to the size of the output transformer. The bigger, the better it is for bass reproduction. You see humungous output transformers on Audio Note Japan & CAT power amps. I don't think that is just for show or to make the owner's life difficult hauling those amps around; i think it is done deliberately for better/best bass reproduction. The QS amps just don't seem to have large output power transformers & simply based on this I get the feeling that their bass is going to be on the light side for a Wilson speaker.
At the 2013 RMAF i attended, Dave Wilson showed off his Alexandria speakers driven by VTL Siegfrieds (yeah, these are probably in the "unobtainium" region) & the sound was very good.
Looking at the VTL amp specs, it seems that, weight-wise, they are at least 1lb per 1W & it "appears" that this weight is in the output power transformers (I cannot confirm this). This seems to be better for bass frequencies.
Maybe it's better to save up some money & buy a better VTL amp such as a S-200 in, say, used condition?
Like I wrote at the start - just some thoughts based on my experience of listening to tube amps at shows & at my friends' place & at dealer show-rooms & the info gained by talking to some tube amp designers. Take it at face-value. Thanks.