Problem with lower frequency bass. Please advise.

I am just not getting adequate bass extension. That lower floor is really missing. I have dynaudio focus mk220 II loudspeakers, my source is an oppo 95, and my int amp is a musical fidelity a308. I use synergistic research cables and power cords and one Kaplan cable power cord. My room is approx 15x18 with one side open bc I am in an apartment. When listening, my speakers completely dissappear and I get a soundstage with excellent depth and size. I'm just not getting good enough bass extension and I want to avoid using a sub. Prior to the dynaudios I was using a pair of monitor audio gr10 monitors and the bass was terrific. I didn't have to use my sub (since sold). I switched to the dynaudio bc I wanted floors standers and I really like their sound. The ma's were a little bright and after many years I was ready for a change. Before buying the dyns I auditioned them with my amp but in a different location. The bass was adequate. Any suggestions?