John: You really need to work on your speaker placement. I know that there are TONS of different speaker formula's that one can use, but quite honestly, nothing short of a dedicated purpose built listening room is perfectly symmetrical and / or without variances according to a given formula.
My first suggestion is to get the speakers further apart. Using a monophonic recording of a female voice OR throwing the mono switch on your preamp ( if it has one ), spread the speakers apart just to the point that the center image just begins to get vague. The image should remain solidly in the center, but not pinpoint. While doing this, the speakers should be "flat faced" or forward firing i.e. with no toe-in or toe-out. This will give you some of the "open" sound quality that you are looking for.
Once you've found a good spacing between the speakers, then experiment with the distance from the back wall. What you are looking for here is the point where the voice sounds full yet natural, not lean or "chesty". You should now have a reasonably solid center image with pretty decent tonal balance.
The next step is to play with the angle of the baffle i.e. keeping the speakers flat faced, a little bit of toe-in, etc... The more toe-in that you run, the more vivid the center image and the brighter the sound. The less toe-in that you run, the wider the overall image with a warmer sound. This is how you "fine tune" the speakers to the specifics that you want to hear from your system at the seated listening position.
Doing the above will get you pretty close to where you want to be. I would suggest listening to the system ( in stereo ) as you normally would for a few days and then adjust things accordingly. If the soundstage is too vague, bring the center to center distance between the speakers in a bit more. If the width of the soundstage is too narrow, slightly reduce the angle of toe-in. You get the idea.
It is at this point that very minute adjustments, not only side to side, front to back and / or the angle of the baffle, but also your seated listening height, listening distance and tilt angle of the speaker becomes quite critical. You might end up having to make several different adjustments here over a period of time, but be both patient and methodical in your adjustments.
I think that you've got quite a bit of room for improvement in this area. Using this approach should net you sizeable gains without having to spend anything other than time and effort. It will optimize your system for what you already have, giving you the greatest return on your initial investment.
Once you've got that done, this will tell you whether or not you feel the need to look into replacing your existing cabling. I won't go into specifics here, but what i will say is that it has been my experience that good cabling can make very noticeable differences in not only what we hear, but how much we enjoy our systems. In my opinion, you've got plenty of room to move in this category also.
Having said that, i would recommend working on a "first things first" basis and start with better room / speaker / listening position integration. Once you get the system to the point where it is doing the best that it can with what you've got, you'll be in a better position to make more consistent comparisons between various cable changes if / when they should occur. Trying to change too many things at one time can make for more questions than answers and / or a misinterpretation of what is causing what. Sean
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