shorten NBS AC cable

I suppose it has to do with the design/build of particular cables. With something like the Shunyata, the insulation includes material that absorbs stray radiation of RFI (the way ferrite beads do the same), so shortening the cable will reduce the benefit of that kind of treatment).

Also, because the manufacturer cannot know what kind of skill is possessed by the person reterminating the cable and the quality of parts that will be used, I can see why they would recommend against cutting the cable even if there were no design considerations.

Depending on the power cable and its design, some sound worse at one meter. I owned a 1 meter Python Helix cord from Shunyata and found that to be the case versus a 1.8 meter. Any benefit in sound a power cord lends may be impacted by halving it's length. Van Den Hul claims the same thing with their power cords.

I just bought an Audience PowerChord that the seller had shortened and reconnected the plug by a "professional" musical instrument repair man. Curious as to the validity of such a mod, the president of Audience responded that any reconnection of Audience cables made it no longer perform to audience's exacting standards. So, I would not risk cutting your cable and reconnecting with new plugs.