Speaker Upgrade, Vandy 3a, Thiel 3.6 ect

I am a Vandersteen 3A Signature owner who mates them with a Pass Aleph 4 amplifier and a Convergent Audio Technology SL-1 Ultimate preamp, so I have top equipment. That said, in the months I have owned these speakers, I have had a great deal of trouble in getting them to really sing in my room. It is not that I don't think that it is possible, but it has been really hard work. As I was more familiar with the Vandersteen 3 prior to purchasing the 3A Signature, and since the 3 is one of the most dynamic speakers with an extremely powerful and deep, but slightly bloated low end, I was surprised that when I got the 3A Signature home, it was quite polite, had so-so dynamics and while spectrally neutral and more extended on the top end than the 3, it was lacking "snap", immediacy and transparency. Part of the problem is the amp which, unlike yours, is by no means bright and while it is one of the finest amps around, does not possess stunning dynamics, but my previous speakers didn't sound like this! I have been working to find interconnects and speaker cables which will bring the midrange forward and add the sparkle that is missing. You probably won't have this problem if your speakers are bright. I would encourage you to listen carefully before buying and to believe what your ears are telling you, and to not invest more trust in the reputation of these speakers than in what you hear. If possible, listen with your own amp before buying. You might consider a Vandersteen 3 which can be had used for under $1000 now, if you find the 3A Signature too "refined".