Problem SOLVED. Finally. Thanks to everyone who responded, it got my mind jogging and, I guess as many people suspected, my speaker setup was to blame. Apparently, my initial problem was the room itself; I knew this somewhat early on because whenever I clapped my hands in the room, I could hear echoes in the upper frequency range that lasted for quite a while. What I didn't know was how negatively this affected the room, and how fatiguing it made my system.
Initially, I had set up the Ohm's correctly (with the tweeters crossing a few feet in front of me), but I noticed that vocals, especially female vocals, along with the upper registers in general, had a sort of hottish tinge to them. I thought my Eighth Nerve Response treatments would solve this problem, which they did help slightly, but when I clapped my hands I still had that same upper-frequency echo reverberating for about half a second in my pretty small 12x14' room. My speakers were still relatively new, so I kept messing with speaker orientation, and after a while I found that if I pointed the tweeters and crossed them closer to my ears (about a foot to a foot and a half in front of them), it would appear to make the hotness that I referred to before go away, and in a way it did or at least appeared to. But, I think the problem with that and the reason why I still found the music fatiguing was that I was not only receiving more high-frequencies directly at my ears but the room was still making the sound itself hot, so these two factors combined made my system even more fatiguing than before.
Recently, I got a set of three GIK 242 panels and installed them all on one wall of my room; immediately, the echo I referred to before was gone. I figured this would solve the problem, and the fatigue would be gone. I was wrong, and I was wrong because my speakers were still oriented in such a way as to try to make up for the shortcomings of the room. After some placement experimentation today, I decided to try them in the original way I had them at first (crossing a few feet in front of me), and everything snapped into place, the soundstage, image focus, etc. I also pulled thme a few inches farther away from the wall, which lightened the bass a bit, a good thing seeing as they had been a bit boomy before because they were too close. In any case, I have been listening now for over an hour with no fatigue whatsoever, and finally the investment I put into this system no longer seems like a huge letdown or a fancy once-in-a-while toy. I am enjoying and connecting to the music so much more than I was before it is like night and day.
This whole experience has shown me both the importance of room tuning and acoustics, as well as the need to be open-minded to experimentation and continual evaluation and re-evaluation of one's components before coming to hasty judgements. If I had been less patient, I would have sold my Ohm's and blamed the problem on the speakers or source, (and I would be lying if I said I had never been tempted to do exactly this) when in fact the problem was quite easily fixable, but because I had already owned these speakers for about three months, experimenting with placement was something I was kind of reluctant to do because I did it a lot when I first got the speakers and figured that I had already found the "optimal" setup for my room.
