What could be instead of side walls?

Although it's hard for me to understand your situation from your description without some clarification, I'm not sure I read it the same way as Rives. It reads to me as if both your speakers are actually quite far away, in your estimation, from both of the side walls. I'm getting that if you moved each speaker closer to the sides, they would become too far apart from each other in the middle, and if you moved the whole system closer toward one corner, you would have an asymmetrical left/right proximity imbalance regarding the side walls. You seem to ask if this is a good thing, or whether you should introduce closer side boundaries somehow. There also seems to be some possibility as to whether maybe your side walls are of unequal lengths or heights, or maybe aren't parallel.

In general, with the vast majority of typical direct-radiating box-type speakers, having a large distance from the speakers to the side walls would be a desirable set-up situation (as would equal distancing from the sides). If the distances are large (over 5-6 feet), then I doubt any asymmetricality would cause any problems (and non-parallel could actually help). If that describes your layout, then I would focus first on speaker separation and aiming, listening chair positioning, and any possibly interfering room furnishings between the speakers and the chair. Also, the floor should not be a bare acoustically reflective surface in front of the speakers, but covered with a rug or carpet, if it is not already. Your description does seem to indicate that your speakers are not too close to the front wall.

You should let us know what model the speakers are in this case, the size and shape of the room, what the treatments and furnishings near the speakers are, exactly how the speakers are positioned and aimed, relative to the room, the listener, and each other, and also the listener position relative to both the room and any large furnishings. Specific measurements and dimensions would be nice. Also, a more detailed description of the symptoms you are hearing would be helpful to us.

Can't agree with Oz's suggestion about introducing side panels, but he's absolutely right about your speaker separation. A chaotic, out-of-focus stage as you described would definitely result from listening at only 5' away while having a separation of twice that much. Try to move your listening position at least a couple of feet farther away if you can without positioning your head closer than two feet from the rear wall, but in either case, do what Oz says and try moving the speakers so they form an approximate equalateral triangle with the listener, then tweak the separation from there. You also don't tell us about the speaker aiming, but straight-ahead firing will create a more diffuse soundstage, while toeing them in to point more at your ears will increase focus. In addition, in a floor covering of some kind is very desirable to use on top of your wooden floor to provide some acoustic absorption, and should be placed underneath the speakers as well to break up the energy transfer from the cabinets to the springy floor (do not use speaker spikes in this situation, but mass-loading the cabinet bottoms with sandbags, if applicable, could help). If you can't get a rug to go beneath the speakers as well as in front of them, then maybe try out Vibrapods underneath, but as it is now, your floor is probably storing and releasing delayed energy, both acoustically, and vibrationally back into the speaker cabinets. The heavier weight of rug you get, the more it will help this. Good luck, and let us know what you do and what happens.

You are perfectly correct as far as that goes, Cdc - and that's just the problem, when it comes to springy suspended wooden floors. Many speaker manufactures will specify in their owner's manuals that the spikes should be omitted in cases like this. Rigid coupling of the speaker to a non-resonant substrate, such as a poured concrete foundation underlying a carpeted first-level floor, is of course the ideal situation. But when it comes to a flexible, resonant floor like the one Marakanetz seems to be cursed with, attempting to break the mechanical coupling is about all one can try to do, as it will sound better this way even if it means the speakers are then not quite as rigidly positionally fixed in space while the music plays (which they wouldn't entirely be anyway, if the floor they were fixed to was flexing along). You do not want this type of floor acting like the soundboard of an acoustic stringed instrument, with the speaker's drivers as the strings, and the cabinet spikes as the bridge. You've got to attempt to "float" the speaker in this case, at least with near-full range floorstanders . (In my old apartment [and it was literally old], I used to fantasize about rigging up some kind of hanging cable harness to suspend my floorstanding speakers from the ceiling! Lucky me, now that I have the system set up in my new digs on a foundational substrate - when I finally decide on my speakers' ultimate positioning, I'll even be able to actually use my spikes!)