Agree, the improvement in imaging, detail and focus is significant and well worth the money. They seem to be based on the principle of dither, but how exactly they work is a mystery. That they do work however is clear. Mine were added following the path recommended by SR which I think was front walls, side walls and ceiling, speaker kit, something like that.
In a larger or odd shaped room I would suggest starting with the speaker kit. This should definitely work because no matter what size or shape room they go in the same place, on the speakers. They go on the front, sides and back. The recommended locations do work out well, and if you experiment will probably find small adjustments in placement produce fascinating changes in presentation. Not night and day but just fascinating, because why would an inch or two possibly make any difference? But it does.
One or two Speaker Kits will be enough to experiment. HFT come in different versions tailored to different applications. The Speaker Kit comes with several. This way you can try some on the walls and ceiling, which even a couple should be enough to get some idea how a full set would work.
You can split a Kit and use one with half on each speaker. But I would start with two since that will give you a lot more to play with and try on the walls. Even though it is a speaker kit I would start with them on the walls. Because I like to start with where something is least likely to work. Look at what SR recommends, match up with what you have, try and see. Then try them on the speakers.
