@sasho - I have no experience with the Neotech NES 3002 2 x 9 AWG speaker cable cable.
While it may well be a very good cable i.e. compared to other brands on the market, it’s touted benefits are proabably due in large part to the UP-OCC copper used
Based on what I see of the cable geometry, compared to my Helix AIR cables, there is an aweful lot of Teflon insulation used on seperate wires, together with PVC insulation, which would contribute to high DK values, so the overall the capacitance of this cables would probably be quite high like Kimber Kables wire,
- which is not a problem with Tube amps, but some high current solid state amps might not like this cable.
- Because of the high DK values the clarity, details and image would not be as good as the Helix AIR geometry
The Helix AIR approach to cables provide exceptionally low Dielectric Constant (DK) values, which mitigates cable distortions to extremely low levels, making it one of the best approaches for clarity, details and imaging
But - If the Helix DIY AIR is not for you, I would recommend taking a look at Zavfino cables. They use UP-OCC solid copper coupled with good cable geometry and their high end use Graphine, which apparently results in lower DK levels
As for my choice of UP-OCC wire
- OCC6N Copper Hook-Up Wire (partsconnexion.com)
- Neotech Copper PTFE Solid Hook-Up Wire (partsconnexion.com)
I have tried both of these in the Helix AIR geometry cables and #1 was noticebly better, but not by a HUGE margin, just a little more dynamic
Hope that helps - Steve