Stabie: you're quite right, a sturdy cabinet using a dense material such as MDF in sufficient thickness and both adqequately and correctly braced is nearly always good enough. Right again on the crossover / impedance: if you go beyond a two-way system, parallel wiring will usually take the effective impedance below what most amps can handle, in many multi-driver cases below what ANY amp can handle. And this goes to the nut on true bi/tri-amping (I say "true" which means low-level electronic crossover and discrete amps for each driver group as opposed to the phony bi-amping often used today where the same amp feeds signal to the crossover section for each driver group). I did true bi-amping on my first "serious" stereo system, and am unlikely to repeat. The gain in transparency and speed of response was audibly noticeable, but no driver is uniform throughout its frequency response or impedance. Practical meaning: truly bi or tri-amped systems will also reproduce the peaks and valleys in the response curves which a well-designed crossover will correct, and due to the impedance variations, a true bi or tri-amped system will be out of balance between driver SPLs at various points in the frequency response.

Lena: for most home apps with normal cubic spaces (in which I would include my own, even with an open plan and a 16 foot ceiling) I am not a fan of the large multi-array speakers such as your top of the line DynAudio (there are many others from which to choose). I would always choose a high-quality 2-4 driver design for sound preference and not just price performance. If you really want to test DIY, sticking to a limited number of drivers and a rpoven cabinet design is even more critical.

Jason: seems that we have similar opinions on driver suppliers, in particular that it is the tweeters that separate the wheat from the chaff. I've heard all of the main ribbon tweeters. The good ones such as Raven 9500 are MIGHTY sweet. Problem is that, to my ears, they are just not as seamless with conventional bass / mid-bass drivers comapred with high quality domes.