Getting a small room right can be very difficult, and depending on the speakers, can be near impossible, and to top things off, you have a square room. This is not a cable issue, it is an acoustics issue. Panel placement and usage will need to be careful, you may need base traps, and your sweet spot is going to be smaller. That bass suck-out you experienced sounds like a listening position/speaker issue.
You will have to navigate your acoustics path a bit on your own. There are those out there who promote "live" rooms, equating music playback to music generation (it is not), but they are also right that the other camp can go overboard on dampening, though it is a much safer path. "Live" rooms tend to be inconsistent and create a sound of their own. Problem with that is it may sound great with some recordings, and awful with others. It won't be what is on the recording. A more balanced implementation with controlled reflections allows you to get all the timing information required for accurate placement (soundstage) as intended on the recording, while recreating the illusion of being in a space where the music is being played.
You will have to navigate your acoustics path a bit on your own. There are those out there who promote "live" rooms, equating music playback to music generation (it is not), but they are also right that the other camp can go overboard on dampening, though it is a much safer path. "Live" rooms tend to be inconsistent and create a sound of their own. Problem with that is it may sound great with some recordings, and awful with others. It won't be what is on the recording. A more balanced implementation with controlled reflections allows you to get all the timing information required for accurate placement (soundstage) as intended on the recording, while recreating the illusion of being in a space where the music is being played.

