The 5As are designed to be bi-wired, and if you want, bi-amped. Just to digress for a minute, the 3's on down the Vandersteen line are also designed this way. However, with them, the division is between the woofers and the mids/hi's. Since the 5's and 5A's have a powered sub the division is between the mids and the tweeter. There is no speaker wire going to the sub woofer in the 5 or 5A. Which, if I understand some of the above posts, is what is confusing some of you.
When I had 3A sigs. I went from a bi-wire configuration to a vertical bi-amp configuration and the improvement was dramatic. So much so, I would advise anyone with 3A's to give it a try. Since I had the amps available I continued the vertical bi-amping with my 5A's. In this case the difference is very slight and not worth purchasing a new amp to try it.
When I had 3A sigs. I went from a bi-wire configuration to a vertical bi-amp configuration and the improvement was dramatic. So much so, I would advise anyone with 3A's to give it a try. Since I had the amps available I continued the vertical bi-amping with my 5A's. In this case the difference is very slight and not worth purchasing a new amp to try it.