I can't imagine that the your system in the room you describe sounds neutral or natural. There's no way the Thiels can produce adequate bass or lower midrange to properly pressurize that room. I suspect what you hear is way too much upper midrange/treble info.
Obviously changing the electronics is not a solution. You could stick a hundred tubes into the system and it still won't sound natural. You need speakers that would work well in that specific room. I'm thinking something that can move a lot of air. You should consider the big VMPS towers, the large Legacy models, the Zu models with multiple bass drivers or the big PBN models.
I've expressed some strong opinions and there's always the possibility that I could be totally wrong, but I suggest you try the following experiment. It will cost you nothing but time and effort. Move your speakers so that they are within 1 to 2 feet of a rear wall in order to get some room reinforcement in the bass. Move your listening position such that it replicates your normal listening distance. Don't make any snap judgments. Give yourself some time to acclimate to the sound. You may have to play with the exact distance between the wall and the speaker to smooth out the bass. After you have a handle with the sound of this setup change your listening position to the wall opposite the speaker and have your head positioned within a foot or two of the wall. See how it sounds. In the end you may prefer your original setup, but the experiment will give you a glimpse of how your room will sound with the speakers coupled to the room rather than divorce from, which is your current setup.
Obviously changing the electronics is not a solution. You could stick a hundred tubes into the system and it still won't sound natural. You need speakers that would work well in that specific room. I'm thinking something that can move a lot of air. You should consider the big VMPS towers, the large Legacy models, the Zu models with multiple bass drivers or the big PBN models.
I've expressed some strong opinions and there's always the possibility that I could be totally wrong, but I suggest you try the following experiment. It will cost you nothing but time and effort. Move your speakers so that they are within 1 to 2 feet of a rear wall in order to get some room reinforcement in the bass. Move your listening position such that it replicates your normal listening distance. Don't make any snap judgments. Give yourself some time to acclimate to the sound. You may have to play with the exact distance between the wall and the speaker to smooth out the bass. After you have a handle with the sound of this setup change your listening position to the wall opposite the speaker and have your head positioned within a foot or two of the wall. See how it sounds. In the end you may prefer your original setup, but the experiment will give you a glimpse of how your room will sound with the speakers coupled to the room rather than divorce from, which is your current setup.