Welcome! This is a great place to learn and get help and advice.
Be warned! You may not be able to maintain that low-fi mid-fi status here for long. Once you start down this road it is very hard to stop. You can consider Danny's (GR Research) speakers a gateway drug to the world of Hi-fidelity audio. Your bank account will hate you.

Because once you hear them you will realize that you need a better amp and then a better??? and on it goes. You get the idea.
Is there a flat pack available for the Xls? I haven't seen it. But it looks to be an easy build. You can do it. Ask any questions you may have here.