According to the Von Schweikert Audio website, the Unified 2 mk 2 speakers are rated at 88 dB/w/m at 4 ohms, recommended power 50 - 200 watts. The Vitus amp appears to be a well built solid state design and is rated to 4 ohm loads.
According to the raw numbers I'd guess (depending on how close you listen and how dampened the room is), 50 watts at 4 ohms would produce about 98 dB (class A mode). Again according to the numbers in class A/B mode the speakers would be the limiting factor (same as you have now which is around 104 dB). Therefore you'd be losing about 1/3rd of the ultimate output.
Most audiophiles do critical listening at average of 85 dB, but music is made up of peaks which require lots of power. Most say that live music can peak between 105 and 110 dB (which for your speakers/room would require 270 to 700 watts, thus not the best speakers for your room). So the big question is how loud to you normally listen? If you have a sound pressure meter (or app on a smart phone) you can get a tell if that is loud enough for you.
The big concern when running close to the amp's limit is how does the amp behaves at that limit. Solid state amps tend to 'clip' which means hitting a hard limit which can be very hard on drivers (probably the leading cause of speaker failure). In class A you would be limiting the dynamics of the music given your room size without risking speaker damage.
Note that class A design is very inefficient, so the amp would generate lots of heat.
