Audiophiles hifi appreciation thread old and new

Change the dimensions of the room. You can change the way the speakers interact with the room by moving them but there are some wavelengths that will be cancelling themselves out because of the size of the room. They are called room modes. It's quite likely that you have a pronounced lower bass which makes you think the mid bass is too low.

What @Airhead said. You can also attempt to lessen them with absorption materials (not very real-life friendly) or roughly mitigate the effects with EQ/DSP.
Moving the speakers to where they’re designed to be, relative to walls/corners should help get their ‘natural’ sound.