It sounds like you want some guitar tones that are clean on the edge of break-up with smooth sustain. As mentioned, an good amp sim would be a start since your room is box/square shaped and you don't have treatment. Along with the new Digidesign unit mentioned, the Softube Vintage Amp room collection is a nice sim. If you go the amp route you'll need to isolate a small area for just tracking the amp so a small combo is in order along, with some absorption. The Rebel 20 has great tone but, it's a loud amp although I have not heard it on the 1-watt setting. Another good amp is the Fender Super champ XD a small "Hybrid" combo (tube/modeling) I was very surprised at the smooth saturation I got out of this amp at low volumes for recording or a Vox AC15 for that chimey breakup.
Here's a quick isolation idea:
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