Changes made: 2-way stereo electronic crossover now in place, feeding my Marantz 8b (High and Mid range) and Linn LK85 (Low range). Crossover frequency is approx 800Hz using a 24dB/octave slope and Linkwitz-Riley style response.
What a spectacular difference to the output from my Heresy IIIs. Bass response is well improved (which I always felt was my systems greatest weakness when just running 'the 8b with the Heresy's and the primary driver behind making the change to bi-amping with solid-state on the LF), but the most surprising and even more pleasing difference is the improvement in separation of individual instruments, giving wonderful clarity right across the the entire frequency spectrum. I was expecting some improvement, but I thought my old set-up sounded pretty good and I am really quite amazed at what a difference this change has made.
The only downside is that my Ashly XR-1000 is getting a little long in the tooth and whereas, in the past, my system was completely silent with no active source, I now have a very feint hiss - imperceptible unless your ear is against the speaker, but it makes me wonder if its caps might need replacement and if so, what additional listening bliss might lie beyond that modification (or a switch to a new Marchand, or similar).
Anyone thinking about bi-amping Heresy IIIs would receive my absolute recommendation to go for it. And if you weren't thinking about it, maybe it's time to start!
Nick