Maybe it was two years ago, I don't recall. I think I got my 800 with the switch around 2 years ago.
Update: For the fun of testing, I moved my 500 which was stacked on top of the 600 at the 6 O'clock position over on top of the 800 at the 9 O'clock position. It seems to have really elevated the mid/upper bass ranges in the room, but I feel like I want a little more at the rear position where the 500 was before. It sounds so nice that I may have to order in another 500 to stack on the 600 and leave the current 500 where it is on the 800.
Honestly, I think this is getting a little exaggerated and out of mental control. But the sound is so much of a draw that I cannot resist. The stacked subs is quite impressive and once you go that route, it's hard to go back to a single sub, no matter how large it is. It's as close to a live venue as you can get to, maybe it's even just as good or better.
