Brian,
thank you for the kind words.
my current speakers do not allow any bi-amping, although at 97db, 7 ohm they don't need it either. the single 108 stereo did a fine job even in my large room. the big mono's do an even better job. i used the pair of stereo 108's back in 2004-2005 when i owned Von Schweikert VR9SE's which did allow for bi-amping. it did work very well.
reading about your Sonics by Joachim Gerhard speakers they appear to be a good match for the 108 at 90db, 4 ohm. i read the Stereophile review about them and would expect that pairing to be really nice.
I would expect that the dart 108 would retain some of the tube magic from the Cary while lowering the noise floor and adding articulation to the low registers.
looking over your website I was impressed. i'm familiar with some of your work and can see where you are coming from with your interest in the dart 108. i will look forward to acquiring more of your catalogue.