Rel sub cable options

I want to upgrade the neutrik cable on my Rel Storm III. Has anyone compared the Kimber Kable and Rel Blue cables? The Rel is almost twice as much (but also twice as long).
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GutWire in Canada has just finished creating the GutWire Congruence REL subwoofer cable. It isn't on the web anywhere yet, but will go up to our site soon. I've uploaded a picture here:

It will be $450 CAD for a 8ft cable and $20 CAD per additional foot.

For me, I prefer it over the REL Bassline Blue. The nice thing is that you're not having the signal go through so much extra cable as the REL cables are very long. You order the length you want. I find the sub disappears incredibly well with this cable which really adds to the transparency.

Configuration: Red (right), White (left – equivalent of the REL yellow wire), Black (ground)

• Conductors: Multi-Stranded High Purity Oxygen Free Copper
• Insulation: Low dielectric Polyethylene
• Shielding: 100% Copper Braided Shielding
• Connector: Direct gold-plated Spade

I haven't heard the Kimber, so I can't compare to that, but I thought I'd mention this as nobody would know yet that GutWire is a great option because it is so new. I'm using the very first one on the market.
Regarding the extra long stock REL is actually VERY easy to cut it down in length to any size that is needed. I think there is a nice increase in SQ when one cuts the cable to the minimum length required. Just be careful you don't cut too much..:0)
That's true Daveyf, you can definitely cut down the length on the REL cable and that would work very well, but you'd lose the factory terminated spades. You'd just have to re-terminate with the connectors of your choice or go bare wire.
I just had audioArtcable make me a pair for my T-3s,I was blown away by the increase in low bass power and dynamics.I upgraded to the SC-5SE on Robs advice and I have no regrets.
Everest, I don't know what cable you are supplying your customers, BUT the cable that came with my REL was not terminated at the amp end. I added spades as an upgrade.
Daveyf, I was comparing the GutWire cable versus the upgraded REL Bassline Blue which comes with spades. The REL cable that is included with REL subs provides bare wire on the amp end.
I've been using a Rel Stadium 2 for over 10 years and just added another one (big improvement with room node reduction and increased smoothness overall) but I called Frank at Signal Cable, told him the length(s) I needed and he made me custom lengths to replace the stock Rel cables.
*Dramatic difference? No.
*Well worthwhile in extra dynamics,speed and detail: yes.
Am not familiar with the brands/models you've mentioned so I can't compare but changing from the stock cable seems a likely improvement... FWIW, I will never use stock power cords nor will I buy any component with captive power cords unless I swap in an IEC connector to allow aftermarket cables as the improvements are profound; but that's a whole other can of worms not worth opening. Good luck.
I love Neutrik connectors (years in pro audio) and find it's really simple to build
cables using these things. Get a shrink wrap setup (for the amp end) and off you
go...I replaced my REL cable with some well designed cable (Canare...made from
ground up small birds) I bought someplace and although it's not solid core like
most of my other hifi stuff, it sounds great. The REL was working fine prior to my
"new" cable, but since it's a sub these things are harder to quantify...I
will say the "speed," accuracy, tonal balance, odor, power, subtlety of
nuanced dynamic variables, increase in variability of non variable variables, and
dust rejection of the open weave speaker grill have all improved by exactly (I
measured this with an Exactness Measuring Device) 4.3%. Totally worth it.
You may want to check your math, my calculations show 5.2% ever more better :)
Hey everyone. I just installed 3 m Analysis Plus REL Theater 4 cables for hi-level connection from my amps to my pair of REL S/510. 
I am considering buying the 6 foot cables from Frank at signal hi-fi/signal cable and wonder if anyone has compared these two. Obviously, I would be keeping the ones I like better and returning the ones that lose the competition.
@wolf_garcia , it was a complicated math problem and took years of a/b research.  Then to quantify the value, sheesh.  I’m surprised it didn’t take longer.

@kbuech , Frank is awesome to work with and makes nice cables.  You ought to give them a try.  
Thanks for that, @b_limo , that’s just what I needed to hear. I was leaning toward having them both at home and comparing the two and you nudged me all the way :-)
I will post my impressions here once I have a chance to listen to them both.
I have REL cables made by Signal and also by Audio Art. Both less expensive than the bassline blue. I use them in different systems. Haven’t had chance to compare. The AA cost about double the Signal but use better connector and wire seems higher quality but I like both

Re: Analysis Plus REL cables vs. Signal Audio REL Speakon cables. 

After hours of auditioning each set of cables, giving them each at least 100 hours of break in time on my pair of REL S/510s, I returned The Analysis Plus REL cables that I purchased on a 30-day trial from The Cable Company. Frank’s Signal Audio REL cables are just better in every way. Deeper and yet more articulate bass, more three-dimensional space to the soundstage, and all the stuff that REL subwoofers are known for.

As they say, your mileage may vary, but I am a big fan of the Signal Audio REL Speakon Cables and give them my highest recommendation!

Signal...I have the Analysis plus one as well, but prefer the Signal cable.  
I just picked up a pair of S/510s that I'll be driving from PS Audio M1200 monoblocs.  I have some extra Kimber 8TC lying around and was planning on using a single run of each to each sub.  Using the Speakon 4-pole connector, I plan on using 8 conductors split in half for the 2 positive terminals and the other 8 conductors split in half for the 2 negative terminals; so there will be 4 individual conductors on each pole of the Speakon.

REL makes a big deal about talking about the resistance of the cable in concert with their input design.  Am I using too much wire and will it be a problem?  Almost everything I see for sale is only 2 conductors per pole.

Good idea?  Bad idea?  I already own all the pieces so there is no cost outlay.
After my post, I found the 'Russ Andrews' REL cable made from 8TC.  That is almost exactly what I'm going to do except.....where he has 2 leads for a right + channel and a left + channel, I'll combine the wires into one lead for a single + connection.  As I said, I'm using monoblocs.

So maybe I'm all set!? :-)
Signal Cable does not state what kind of solder it uses. I am wondering if it just regular and not pure silver solder as with the Rel Bassline Blue.