So, for those who are interested, I took Johnny R's advice and ended up with an asymmetrical placement for my Treos based on the Vandersteen manual's math. Compared to my initial setup (which I just eyeballed), it is night and day! The soundstage is vastly improved, as is the bass response. I am very surprised/impressed by how much these simple adjustments have improved the overall sound and experience of the Treos. Really starting to love these things!
I am still experimenting with the listening height, and will see what works best for my listening room.
@audioconnection I have my Treos sitting on three Herbie's Decoupling Gliders (
http://herbiesaudiolab.net/spkrfeet.htm). These raise the speakers about 5/16" (8mm) off the floor, but don't effect tilt. Do you think I need to take this into consideration when setting the listening height/tailback adjustment? The Vandersteen chart situates me at 7 or 8 washers, and I've erred on the low end due to the added height of the gliders. So far, it sounds pretty damn good to me, but will experiment more and see what works best. Would appreciate any feedback.
@audioconnection Thanks for the Hegel D12 suggestion. Something to consider down the road for sure.