Glad to hear you have pulled out the nOhr gear to do some configuring and listening! Many members have done a lot of listening to nOhr gear over the years and it has proven to be well worth it. Nowadays, nOrh gear is a part of history, and also a part of living history for those who still own it. Manufactured in Thailand, by mostly Thais, with amazing lathed marble cabinets, etc.
The CD-1 was basically a Cal Audio Delta Sigma Plus or something along those lines, made by the same manufacturer.
The famous Wood 3.0s are a legend of some audio shows (I have a pair of Teak Prism 3.0s).
I use 2600 for my crossover when using the Multiamps and the Marble 9.0s in Active Bi-Amp wiring mode. That has been recommended with 2500 also mentioned. It depends on placement and the room itself and you have to judge by your ears. But that value should be a safe starting place.
About the MultiAmps. These chip amps are pretty good for what you paid for them, after all you can Active Bi-amp the wonderful Mable 9.0s with them. BUT...the chips are attached to a heatsink which is attached to a plate which CAN FLEX. My MultiAmps went back to the actual 'manufacturer', Curt Wishman, for an overhaul which included taking care of any case flex. He really over-re-engineered the amp structure and maybe even some other things. DO NOT move the case by the handles on the front plate. It seems that the amp was a good idea at the time, which was not mechanically designed by Michael Barnes or Curt Wishman. This design did not work in the real world (the flex impinging on the chip). Curt merely manufactured in Bangkok, but he also came through for those that needed repairs, backed up by Michael Barnes.
I have been careful with my gear, kept it inside climate controlled rooms, and it has done very well over the years.
Please, others chime in on DTH's questions!