I currently run a cdx, 82, hicap,180 into Kef 105/3 with naim nac5 cable.
I have been offered another 180 for good money but i assume i cannot wire it in without an active crossover? Would there be any benefit to me doing that at all if its possible?
I believe the 105/3 has two pairs of terminals. That means you can connect two 180s in a passive biamp configuration. Just connect both 180s to your Hicap and then run two sets of speaker leads, having removed the connectors between the two pairs of terminals on the speakers.
That said, you’d very likely be better swapping the 180 for a 250; one big one is generally better than two little ones.
People do passively biamp biwirable speakers, and some claim benefits. Personally I’m dubious as to benefit, and certainly wouldn’t advocate spending money buying an amp to do that, but if you have one available for no cost there is nothing to lose trying it.
For active the first question is whether you can remove the speaker’s existing crossover, whether from the back, or perhaps through a driver aperture…