few comments to your topics:
1.) PCs 230V AC
I found no difference for neutral using 2x 1,3sqmm or 1x 2,5sqmm Jantzen wire.
Be aware, being in 230V country, the PE (Ground-) wire must be minimum the size of the L/N conductors. With the double neutral helix like Steve proposes, this is not given.
If the extra expenses for Neotech OCC as N is worth the gain in sound, I do not beleave, since you already have purchased the MIL wire. Solid core vs stranded- well, my experience is, that solid core thicker than 16 AWG is not “sounding” good in PCs (230V country). This is the reason, I use stranded Jantzen silver plated wire as neutral.
Its all personal taste and component synergies. In some applications I do not like the helix PC with Neotech OCC 2x 16 AWG at all. Prefere stranded wire in different configuration.
2.) Balanced IC as helix design
I do not believe, the helix design is best suited for balanced IC, unless you do 2 single ended (RCA) cables for 1 XLR cable. One, where centre wire is ve+ and an other where centre wire carries ve-.
The ve+ and ve- in the helix design are “undefined “ running next to each other.
A much better design for Balance IC is the VH Audio receipe, where + and - and GND is “ at controlled distance to each other, having capacity and inductance within the cable “controlled “.
I do not like the Neotech OCC copper wire in the IC’s. Have tried a few different configurations with different wire diameters.
My “best” sounding balanced IC is made according the VH Audio receipt but with 1x 28 AWG and 1x 24 AWG VH Audio OCC silver in cotton wire twisted for ve+ and ve- and 1x 24 and 1x 22 AWG Neotech OCC copper in PTFE as ground.
Connectors are ETI Kyro silver XLR soldered with Cardas solder.
This balanced VH Audio wire with Neutrik silver plated connectors outperforms the Neotech OCC copper in the same design with ETI Kyro plugs easy.
The ETI Kyro XLR plugs are 10x more expensive than the Neutrik. Of course they are not 10x better, but surprisingly audible better, more than I expected.
The Neotech XLR cable sounds impressive and really great Hi-Fi, the VH Audio sounds like “music”
Difficult to describe until you experience it yourself. It’s got NO “silver” sound, it is smoother, richer, more texture, air, ambient and bass is better. Sounds weird? Yes, but that’s what I hear with my ears, my brain, my equipment in my room.
If the equipment and the speakers are not at a very high level, it may be different, since the amount of micro details could show all the flaws in the chain.
just my 2 cents...