Are upgraded power cables for subwoofers worth it?

@sns that looks like a solid option.  What do materials cost on those typically for you and how difficult are they to create? 

@knownothing good call on that.  I figure these were at least OFC but my shunyata stuff is all OCC which is definitely superior.  Was a little skeptical of chi fi stuff actually using OCC but if youve had good results with these I'll have to check them out! 

Yep, purity of metal is important consideration. This diy design can use any type of wire, I've been most happy with twisted runs of VHAudio AirLock sold core OCC copper, this for hot wire, number of runs depend on use, three runs of 18AWG of this equalis 13AWG, neutral I run either same VH Audio or sometimes litz copper OCC, same variety of runs to get to gauge I'm seeking, 10 or 12AWG solid core copper for ground. After trying many AC connectors, some very expensive such as Furutech NCF50 I've found good value/performance with the PartsConnexion Connex, carbon fiber Rhodium connectors. In fact I've gone exclusively to Rhodium on virtually all connectors in my system. Rhodium no maintenance, no oxidation and once over agonizingly long break in most wide open as in both transparency and dynamics, damn things just flow current, voicing comes the wire, equipment tubes, isolation, room, etc. Building of these most difficult issue, reverse twisting of both ground and neutral wire then interweaving them time consuming and requires much patience. The twist is made via placing long fiberglass pole of proper outside diameter in drill, attach wire to pole via tape, reverse drill, wire wraps around pole. Do the same with neutral or multiple neutrals, then you must spread twisted ground so that you can interweave by hand the twisted neutral, Hot wire rides inside twisted ground and neutral, easy part. The reverse twist is what most believe to be special about this design, add in nearly unlimited choices in wire, hook up wire generally used by most. People use this design for interconnects as well, I haven't.  I used to run some over $5k (accounting for inflation, probably more like $7.5K today) AC cables, generally I ran Shunyata, Purist Audio, Synergistic higher or best models, not saying these weren't nice, but the Double Helix simply flow, sound more like no AC cable than the off the shelf. And those I chose to purchase were the best of what I demoed over the decades.

@sns thanks for the detailed instructions.  One of my best friends is a tinkerer that does all my soldering work so I may see if he's up for the job.  If you are saying you're getting high end results at a fraction of the cost, I'm all ears.  The runs would be fairly short for my studio subs so they may be not as time consuming as my second setup where they need 3 meters each.  I'll let you know if I go through with it and the results!