When you decide to replace your 5a's batteries, you may want to consider using the longer-life Lithium version. When I shipped my crossovers to Richard Vandersteen for battery replacement, I included 6 new RadioShack 9V "Ultralife" Lithium batteries (3 per crossover).
Vandersteen 5a battery biased crossovers
I've been using my 5As nearly every day for over 2 and a half years now and I feel they are the best move I ever made in audio. I researched them (and many other speakers)thoroughly before I made my purchase. I must say that everything incorporated in this design makes more sense to me than any other speaker I've encountered(Richard Hardesty's review covers this all very well for those not familiar) The one feature I still wonder about though is the battery biased crossover. How much does this help the sound? I believe that after about 5 years the battery needs to be changed on each crossover. Has anyone here had the 5A long enough that this had to be done? Did you do it yourself or does it require shipping to the factory?( I think the batteries are soldered in place to keep from rattling)Also, has anyone just let this go and not really noticed a difference?