Speaker recommendations for Proprius?

My concern is your square room. It cost me dearly to realise just how much influence room shape has on the tonal response. I was aware of acoustics but didn't think it would have such an impact as it did. I'd had an extension built to the workshop, but I'd lost one foot off the width due to the construction method I'd asked for. The extension was to be my office where amongst other things, I could audition my work. I could not audition a thing! The almost equal height to width caused boom. My posh new office ended up being workshop space, and the workshop got partitioned off to become my office. Being a foot wider with the ceiling height six inches lower solved the boom problem. I used the Amroc calculator to find where to place the partition wall, which gave a room ratio that fitted the "Bolt" area and the "Bonello" response. I went considerably further than most would do to absorb the room mode pressure zones using BBC absorber homemade clones. The room modes are still audible but not as prominent.

There is little that can be done in a domestic situation, and I'm not suggesting you go to the extremes I had to go to. However, if your aim is for good sound, which I think it is, I would seriously look at ways to improve your acoustics. I would be thinking about losing three feet off one floor area dimension - perhaps by fitting something like this?

If you can't, then I'd go for a bass reflex whose port resonates anywhere but the strong frequencies shown on the calculator, somewhere between 70 and 90 Hz.