I would agree with @hickamore on the bass performance of the Signature SE and the benefit of using subs to supplement. I have previously owned both the Focus SE and Aeris. In both cases, while they let out big sound, they did not offer the benefits that quality, properly integrated subs do. I eventually moved away from the larger speakers and into better fitting speakers for the room accommodated by subs. Not only do the subs handle any missing bass information, but it also widens and deepens the soundstage and cleans up room modes and the full frequency spectrum, resulting in additional clarity and an improved performance across the board. Though I moved on from the Aeris being my speaker, I have since become a dealer and now am an official Legacy Audio installer. With that in mind, I have a custom pair of Signature SE coming for my floor in a week or two, as I realize it is more than enough to fill the space when properly integrated with subs, as demonstrated by a customer who traded in their Legacy Classic HD a few months back. Even that was enough in my room when partnered by two subs.
Measurements will also be very helpful, as is walking around the room as others suggest. But especially with the opening to the kitchen on the left side, subs and proper integration will be your best friend in this scenario.
Also, the problem is not with your amp, so disregard anyone who says so. The CODA No.8 is stable down to 2 ohms easily, and Legacy used to use CODA amps for their speakers prior to making their own with ICE modules.