What Gauge of Wire...?

Hi Tiko , I had much the same speaker set up as yours but was using an Onkyo TX-DS939 Receiver and NHT Hdmp2 dipoles for the rears . I never found a high priced speaker cable of any gauge that could even justify the price versus performance with the NHT set up for Home Theater. I ended up using and was more than happy with audio quest cv4 that I bought a bulk roll for under a hundred bucks then used those 4 dollar a pair deltron banana connectors . When I changed homes and re-set up the system in a room with wall to wall carpet I used a bulk roll of monster flat line tucked under the base boards and carpet and it sounded great as well . Unless the metal tweeters in the fronts are giving you too much zing what your using will be fine . I found that the inter-connects in my system made more of a differance in quality of sound than the speaker wires did with the NHTs .(Van den hull Mk11) Or at least they tamed the metal tweeters a little better than they already are . Cheers.

My trick was to run 2 sets of speaker wires [zip cord] to each speaker, one set to the + and one set to the - terminal. Separating the 2 wires by a few inches will reduce capacitance and inductance vs. having the signal paths in close proximity in only 1 cable.

Thank you All for your responses. The information I've got from you is very important for me and is very useful. As I can see there is not much difference (if there is any) in regular and expensive cables. And I will stay with my 14 Gauge Home Depot cables.
But what about Subwoofer cable? It shouldn't be more thicker than the front and surround ones? And what is the best setup: If I have the subs far from my components (10-12 feet far) is it better to leave the SA-3 Amp on the component rack and hook it up to the receiver with say 3 Feet cable, then run the 12 or 14 gauge cables from that Amp to the subs for about 10-12 feet, or the other way bring the Amp closer to the subs having that 12 or 14 gauge speaker cables connected from amp to sub for about 2 feet but run the connection cable 10-12 feet back to the main receiver? Which cable is losing more signal the RCA digital 75 Ohm one which runs from the receiver to the amp or the regular 12-14 gauge ones that connecting the amp to the subs?
Right now I can hear sometimes distorted bass from my subs when the volume gows up and they start making annoying sound like BRRR-BRRR-BRRR... When the volume of the receiver is low, I can get clean and tight bass. What is causing this? Not he wrong Amp>Receiver connecion, or AMP>Subs cables? Or the wrong location of subs? Currently I stock both subs on top of each other. Should I separate them far from each other? One more thing: The subs even at lowe volume are late responsive, like there is a delay between actual real time bass which I see on the TV and the sound come out from subs. All this problems of the Bass are not an issue of cables and connection wires? Or may be proper placements of saubs?
Once again, I deeply Appreciate to everyone for helping me and spending your valuable time to write here.