Outboard crossover? Why not?

I agree with the advantages mentioned and think it's worth emphasizing Erik's comment "Reduced effects of microphonic interactions with the speaker". That translates to blacker background and lower distortions. 
It's a shame that perceived visual issues have resulted in fewer external crossovers, especially since most of them sit right behind the speaker which is pulled out from the wall anyway. Usually they can't be seen from the listening area and even if they are it's less visually imposing than making the cabinet twice as deep for the extra room some require to include the electronics.
The cost of another pair of extra chassis especially with upscale veneers adds significantly to to production cost. So do multiple strands of high quality jumpers like the silver ones that Nola uses. Cheers,
Spencer

erik_squires504 posts08-25-2016 11:14am@bombaywalla 
The Apogee's had no real speaker cabinet though, did they? :) I mean, it was one giant magnet frame.

yes, essentially correct. The cabinet was very wide & about 3 inches thick. And it was very easy to hide the xternal x-over behind that wide frame @  essentially no visual cost. A standard metal box which kept out RFI & EMI did the trick for holding the passive x-over components.

My preference is a fully digital crossover feeding reference grade DAC's and a multi-channel preamp, but I can't afford that at all. :) After that it's passive.

you know I doubt that you will need a preamp as you can find several DACs in the market that have built in digital volume control  that dont compromise sound quality (one such example is DEQX) OR several that have an analog volume control so that you can go straight into an amplifier.

NO Advantage at all , Just raise the price

Active x-overs certainly offer theoretical advantages and (generally speaking) I'm a big believer.  Digital, active x-overs offer even more theoretical advantages and (generally speaking) I'm an even bigger believer.

All passive x-overs (internal or external) present certain issues that demand trade-offs.  Hence the great debate about low order vs high order x-overs.  An active, digital x-over doesn't demand the compromise.  Although (obviously) many here find digital sources (or ADC) a compromise in, and of, itself.  Be that as it may...

My main system is now fed almost exclusively digital program material that's crossed in the digital domain.  There are too many variables at play to say that the x-over scheme is the reason that I prefer the results to any of the many analog based (program material and crossovers) systems I've used in the past, but I prefer the results.

As an aside, several systems use active external x-overs (models from Linkwitz and Salk) come quickly to mind.  Going all the way back to the 80s or early 90s, I think Hales had an external passive x-over option available.