Shielded Speaker Wire 12AWG

I’m a bit confused about your question. Generally, systems put together for high fidelity will be interconnected with speaker cables... built to sound good as opposed just some off the shelf wire with a material requirement. 

Since it sounds like you have a home theater... guessing now... from which you also listen to music. Then you should invest in speaker cables made for the purpose. I recommend looking into Cardas and DHLabs speaker cables. 

For me, I have pretty good quality speaker cables attached to the front three channels and then, the same brand, but lower quality bulk cable for the other channels. 

Given the sonic characteristics of the Marantz and Focal, I recommend looking at Cardas. But ether of these are likely to improve the sonic characteristics of your system for music. It may also be very obvious for HT. But HT is generally less important because one is distracted by the video. But if you are comparing to really cheap wire... then you will probably find it a noticeable improvement. 

From my limited listening experience, other than coax cables used from a TT to a phono preamp, shielded cables can suck the air, the life, out of the sound of the music. That’s even been my experience with shielded power cords.

There are other ways to control EMI other than using a shield. Twisting the wires together. Braiding the wires together. Just to name two methods.

It can be quite complex...

One example:

Iconoclast Cable. The "Wire we Here?"

Terrific information,  I did read about twisting or the wires together. I'll also see if pre-constructed wires fit my budget or if that's down the road. Thanks Jea48 and ghdprentice!

In my opinion and experience shielded speaker cables restrict dynamics! My speaker cables are DIY, the positive and negative are tightly twisted together, no shielding and very short @ 12'' long. Cable material consist of,12 AWG Orange and black Mil-Spec M22759/11 (PTFE) Stranded Silver Plated copper, they look similar to this when finished. Both amp and speaker ends are bare wire. For in the what it's worth category, short speaker cables helps to minimize EMI interference, also try to keep power cords away from speaker cables. 😎

Mike

@cgbgreg 

I agree with others - there is no need to use shielded speaker cables.

Firstly, they carry huge signals compared with interconnects of phono cables, so any RFI will be miniscule in effect.

Secondly, because a speaker cable is a pair of wire bundles, what  affects one bundle pretty much affects the other in the opposite way - this cancellation effect is crucial for very high speed cables like ethernet, which mainly uses unshielded twisted pairs these days.

Thirdly, adding a shield will increase the capacitance of the cable, almost always for the worst.

Speaker cables may benefit from being gently twisted but most often the two conductors will also be separated by about an inch.

Similar arguments apply to balanced interconnects.  Balance is good because it increases the signal to noise ratio.  Shielding is debatable.

If cables must cross other cables, try to do this at right angles to minimise interference.

I'd caution you about centre speakers, but it is off-subject!  Nevertheless, have a good look at this Discover the Surprising Flaw in Center Channel Speakers