I have been following your thread and are waiting for you to come into our shop for a visit as well.
You are not mentioning what sources and how the systems were played which can be a big factor in how a system images and sounds.
Audio Connections system was $1,500 speakers with a $2,500 amp for $4,000k what was the source being demoed and how expensive was that source?
As per the Quest for sound system, $2,500 speakers, plus $1,300 amp as per a Rouge or a Parasound both are good starter amps, however, for the same money there is an amplifier for $995 that beats the stuffings out of both of them.
A Vandersteen sounds totally different than a Kef, if you told Quest for Sound you like the Vandersteen sound it is doubtful you would prefer the Kef. Kef is a much more accurate speaker than a Vandersteen, I am not saying better, more accurate, and has better treble extension, which makes the Kef a more forward sound to the more laid back perspective which is the Vandersteen sound. Apples to Oranges.
I would say that you did not get a good demo with the Kef, as the electronics were not as good as the Belles and a more accurate speaker will show you flaws in the electronics more easily.
You should check out a pair of the Dail Opticons, the Dali offer a remarkable sound, they use a Ribbon super tweeter for detail coupled to a soft dome for wide dispersion and a smooth sound , they also use drivers which have very low distortion and use a new type of powdered magnet material. The Dali Opticon sounds more like a $4,000.00 speaker then a $2,500.00 set! They also have very good bass, and offer a similar warm perspective like the Vandersteens do.
We have a fantastic system using a Nuprime Dac/preamp which sounds incredible and in our system you are getting a state of the art dac along with the preamp, couple that with one of their smaller amps and you have a system with a state of the art dac, a headphone amp, you can upgrade the amp and a stunning pair of Danish speakers that throw a gigantic soundstage. This entire system comes in at $4,795.00 add some good inexpensive cables and you have hit your price point.