I figured I'd compare this XLS 1500 to AudioSource 310, so I ordered the 310. In terms of sound quality, I really can't tell much difference between the two. As far as power, both get loud enough to the point where the extra power of the XLS 1500 just does not matter in my case. Also, not being a pro audio gear, my HK receiver's pre-out voltage wasn't high enough to drive the XLS 1500 to full power.
At the end of the day, as superficial as it may seem, from the aesthetics perspective the XLS is just an eyesore and its weird shape makes it difficult to place among other home audio components, so I think I'll send the XLS back and keep the 310.