As a long time nOrh owner, I strongly recommend finding out if anyone has redesigned the crossover for the 6.9.
I have had the marble 9.0 for almost 13 years now I think. The factory crossover sounded great to my untrained ears when I first got them. However, my listening evolved over time and I also owned much more expensive speakers over a span of 10+ years (i.e. VMPS RM40, Selah RC4, Selah IncredArray) and recognized that the original marble 9.0 was not up to par with some of the speaker on the list. Note that Mr. Barnes used good part such as Multicap so as Jackman indicated, he tried to offer value for the money.
However, the situation changed dramatically once I implemented Dennis Murphy redesign crossover with high quality parts (Alpha core inductor, SonicCap) especially when mated with a pair of 10" sealed subwoofer. The over all sound came pretty close to my pair of IncreadArray within their dynamic range. In an opened environment, the IncredArray clearly better in term of dynamic range but the DM marle 9.0 held its own really well. I can live with the DM marble 9.0 plus a pair of 10" sealed sub and not miss the IncredArray much at all.
The fact that I still held on to the DM marble 9.0 until this day speak loudly of its performance, especially in the mid-bass area. I have yet to hear a speaker that has better midbass. I know there are speakers out there that can produce similar midbass to the marble 9.0 but they probably will cost much more than what I can afford.
This thread brought back a lot of memory for me when I was quite a bit younger. I still cannot believe it has been almost 15 years since I purchased my first pair of nOrh speakers (wood 7.0 I think).