Really Long XLR

You don't need the quad.  The simple pair + shield will do.

Thanks all for your information and recommendations.  Such a spread, where the Mogami W2534 Neglex Quad cable + Connectors will be +/- $250 (CDN) for the project and Audio Envy O’nestian (Matched Pair) will be +/- $2000 (CND) assuming they will build a 45 ft pair.  At almost 10x's the cost, will the Audio Envy cables be "WOW" better than the DYI Mogami?  

OP,

You have a very nice system. I don’t recommend going bottom tier stuff like Blue Jeans, Belkin,, etc or lower tier like Mogami. My experience with these have been they are no better than what you get free. Maybe do it yourself… but consider saving up. You are talking about a critical run, with very sensitive speakers. 
 

Consider the tonal balance and detail of your system. Research and maybe save a liitle. 

If you don’t wanna build your own then I agree with @lalitk that Audio Envy is well worth looking into. 

Look into Audio Envy….I had 30FT RCA, they use OCC copper which is way better than most OFC cables out there. 

Mogami W2534 Neglex Quad cable $1.19/ft. from Redco Audio.

Neutrik NC3FXX-B and NC3FXX-B typically less than $5.00 each. 

I believe Mogami is the preferred cable for professional recording studios.

I would make my own cables from 16 awg Duelund DCA wire.  The wire for a 40' set will cost you $400.  A good set of XLR connectors is $100.  Sheath material another $100.  If you don't have silver solder, another $15.

Jerry

+1 to what Erik listed. Since you're willing to build your own, order some Belden cable from Raw Cable, and Neutrik connectors from Markertek.

I’d use wall/floor mounted plugs and run Mogami or Belkin. This way you can keep the cabling 100% out of the room.

Otherwise, make your own with Mogami or Belkin, shielded is a must at these lengths, and Neutrik connectors.

Besides Parts Express, Parts Connexion (for connectors) you should see what Markertek has.  They often have good discounts on Mogami.

I use the low cost Benchmark XLR cables for long distances. The longest they have is 25-feet but they likely can make longer. I need to buy 2 more long XLRs and waiting until Benchmark stock is back for the 25-foot length.

My other XLR and RCA cables cables are from WyWire and Audience

The cables between my AES-48 compliant preamp and amp do not make a difference with various XLR’s I tried.

Even with my non-AES-48 compliant preamp and amp the Benchmark XLR sounds great.

I keep my gear away from the speakers in both of my 2-channel rigs. Only the amp is close to the speakers.

Try https://www.bluejeanscable.com/store/balancedaudio/index.htm . I have ordered long (~20’) XLR cables from Blue Jeans Cables and they work fine at a reasonable price. Custom lengths are available.

Moving your equipment can from between your speakers can have a very positive effect. I think mine are 25 feet or so. Depending on your system the quality of the interconnects are important. Fortunately this time I was able to buy the same quality level that the rest of my system has.

I would recommend looking for a used set on used cables and Audiogon. Granted the probability is not that high… but something of that length is going to stay on the market for a long time. I think I have seen some in the past.