Hi felipe91,
If you don't mind, I would answer that question. The 1.75 m Sigma NR V2 is around 5 lb and yes, it is very flexible compared with the Hurricane PC. For your information, the Sigma V2 PC elevate the C900u preamp performance a lot, however, for some reasons, this preamp doesn't like...
TWR Obsession pc is great, you need to expend much more to get better performance. The M10x is an step up over the M900u, a much more engaging amp with better grip in bass. I lived 1.5 years with the M900u and the system/room is the same, so I have a real reference.
At least, a good quality pc should be used with the M900u, even if the ground isn’t connected to the amp chassis as some said. That amp (as others) work best with a heavy gauge cable and deserves the best the owner can afford. With the M900u I was using Audioquest Hurricane pc which elevated the...