The thiel manuals are usually helpful and can be downloaded from www.thielaudio.com. The screamingly obvious response to your post is that 6 feet apart is quite wrong. I have owned several Thiels and all operate best at about nine feet apart, and there is a distance apart where moving them further apart causes the sound to go a little lean in the mid-bass, and moving them closer together causes the mid bass to get a little too warm. With Thiel's in my room that ideal spot was with the speakers between 2.6 and 2.7 metres apart. Smaller Thiels liked the 2.6 metre point (eg. 1.5 and 1.6). The 3.5, 2.3 and 2.4 liked 2.7 metres apart.
I would suggest the following. Position the speakers close to the back wall (such as your 1 foot away position) and 2.65 metres apart (pardon my confused metric/imperial state), with no toe-in. Listen to the Thiels from between 10 and 11 feet away. Listen to them in that position and then bring them towards you say 4 to 6 inches at a time, moving your listening position back accordingly. Choose a piece of music that has a well recorded solo vocalist imaging centrally between the speakers. As you move the speakers away from the back wall, the overall soundstage should gain in coherence and in depth, and the vocals should become more natural (less flat and hard) up to a point where the image of the vocalist begins to lose solidity and focus. This should not occur until the speakers are at least 3 feet away from the back wall. Then move the speakers back towards the back wall until you get a solid central image again. Then move the speakers to say 2.6 metres apart, and then out to 2.7 metres apart listening for how the overall character gains or loses coherence. At this point you should be getting a good feel of how to inch the speakers around within this zone to get a good soundstage, solid images and good top-to-bottom coherence (ie. similar levels of driness or warmness through the frequency spectrum). Finally, play around with sitting closer or further away, together with small amounts of toe-in. In general i have always preferred to have Thiel's firing straight ahead, but some rooms require a small amount of toe-in, mainly when the need to have them 9 feet apart causes them to be a bit close to side walls.
Throughout this process, I would not be listening to the bass much, except when trying the "move together/apart" positions, and when moving your listening position forward and back. If you have a very wide back wall you might try moving both speakers left/right (ie. keeping their distance apart constant) to get a smooth bass response - symmetric positioning is usually best with a narrow back wall, but not necessarily so with a wide back wall.
If all this results in poor bass, then I would look at other walls to locate the speakers on, or elsewhere for the problem. For example I cannot imagine the sound of Thiels being good at 1 foot from the back wall, regardless of what that does to bass level - soundstage would be horrible and vocals would be nasal and flat.
I cannot help but ask whether the speakers have had 500 hours of use yet. Thiel's 1.6 and 2.4 take a long time before the bass arrives. Even at 300 hours the bass may not have arrived, depending on how hard you have driven them. Believe me the 2.4 has plenty of bass, but it is quite absent when the speakers are new, and it arrives all of a sudden after 300 to 500 hours of play. Only then can you really do the work to set them up right.
I would suggest the following. Position the speakers close to the back wall (such as your 1 foot away position) and 2.65 metres apart (pardon my confused metric/imperial state), with no toe-in. Listen to the Thiels from between 10 and 11 feet away. Listen to them in that position and then bring them towards you say 4 to 6 inches at a time, moving your listening position back accordingly. Choose a piece of music that has a well recorded solo vocalist imaging centrally between the speakers. As you move the speakers away from the back wall, the overall soundstage should gain in coherence and in depth, and the vocals should become more natural (less flat and hard) up to a point where the image of the vocalist begins to lose solidity and focus. This should not occur until the speakers are at least 3 feet away from the back wall. Then move the speakers back towards the back wall until you get a solid central image again. Then move the speakers to say 2.6 metres apart, and then out to 2.7 metres apart listening for how the overall character gains or loses coherence. At this point you should be getting a good feel of how to inch the speakers around within this zone to get a good soundstage, solid images and good top-to-bottom coherence (ie. similar levels of driness or warmness through the frequency spectrum). Finally, play around with sitting closer or further away, together with small amounts of toe-in. In general i have always preferred to have Thiel's firing straight ahead, but some rooms require a small amount of toe-in, mainly when the need to have them 9 feet apart causes them to be a bit close to side walls.
Throughout this process, I would not be listening to the bass much, except when trying the "move together/apart" positions, and when moving your listening position forward and back. If you have a very wide back wall you might try moving both speakers left/right (ie. keeping their distance apart constant) to get a smooth bass response - symmetric positioning is usually best with a narrow back wall, but not necessarily so with a wide back wall.
If all this results in poor bass, then I would look at other walls to locate the speakers on, or elsewhere for the problem. For example I cannot imagine the sound of Thiels being good at 1 foot from the back wall, regardless of what that does to bass level - soundstage would be horrible and vocals would be nasal and flat.
I cannot help but ask whether the speakers have had 500 hours of use yet. Thiel's 1.6 and 2.4 take a long time before the bass arrives. Even at 300 hours the bass may not have arrived, depending on how hard you have driven them. Believe me the 2.4 has plenty of bass, but it is quite absent when the speakers are new, and it arrives all of a sudden after 300 to 500 hours of play. Only then can you really do the work to set them up right.