I have been tri-amping for years and years. Just changed out the ARC amps for four Pass amps. Two X260.8 mono blocks and two XA30.8 stereo amps.
Out of the pre-amp into a Marchand electronic x-over and to the amps. The x260.8(s) run the woofers. The XA30.8(s) run the mids and the tweets.
The Hartley Reference has no internal x-overs and 3 sets of connections on each speaker. Personally I think it sounds tremendous, but of course I do...its mine.
Regards,
barts