The thing with the strands is more of a quality and heat issue. The more strands, the less ohms/foot you'll have and the less heat you'll have. This comes into play over long distances. More strands also means easier to terminate and your termination will have less resistance becasue solder and crimpes more easily catch many strands rather than a point load contact from a crimp on a single strand wire.
A single strand wire can have the same AWG rating as a mutli-strand wire, but will have more heat and more resistance. At 120v, like in a house, it's not so bad if you drop a few volts over distance, single strand is much cheaper to manufacture, and that's why it's used more in that application. At 12v, it makes a huge difference if you put 50amps in a wire over 25feet (approx distance from battery to back of K5, run nice and neatly), you'll see 1-2volt drop with the average cable out there, try running your audio amps at 10-11 volts, they won't like it very much.
There's all kinds of wire out there, I toke most of my input for the electrical system from a friend of mine who's a EE for Delphi (Automotive group). Back a few years ago, this company in the suite next to us was moving out and they were throwing away and bunch of leftover crap and I saw this 50'+ foot spool of wire in the trash bin. I swiped it. Turned out to be some goofy locomotive cable, extremely high strand count 2awg, but the lowest ohm/foot my EE buddy had ever seen. I looked up a price on it, it's over $100/foot
. I used this wire for my main feed to the back for winches and the 2 polk amplifiers back there, as well as the 500w inverter back there. The 2ga is terminated into the winch terminals along with 6ga out to each amplifier back there and 6ga for the 500w inverter.
I did ALOT of research about voltage drop, heat, resistance, distance and loads back in early 2006 when I was designing the whole electrical system for the K5.
Digging up a few notes (The locomotive cable is the RayChem wire, Vd is Voltage Drop, Vs is starting voltage, i can't find the formula I used, but there's many out there, alot make assumptions about wire size, but if you have the spec of the wire (number of strands and size of strand), it's better to use that, much more accurate)
According to my calculations, using the specifications of the Raychem
cable, I'll be looking at a 2.18%Vd (150amp load, 13.5Vs, 20' length) .
Which is much better then most 2ga cable out there that I can find. The
stuff I probably would have bought, SAE J1127 spec battery wire ends up at
4.25%Vd over 20', at 150amp load starting at 13.5v.
Again, I doubt I'll ever pull 150amps continously, I guess it all comes
down to how much will I pull continuously. The raychem wire does good at
high temps too, it's performance doesn't start dropping significantly
until 180c, (limit of 220c), where most SAE battery wire drops off fast
above 40-60c.
At my guessing of an average load, say 65amps Vd w/the raychem 2ga becomes 1.85% where the J1127 wire is 2.84%. Vd goes much higher if your Vs is 12v as opposed to 13.5v. I better get a good battery and a good alternator that puts out decent amps at idle!
The 65 amps figure is average load I guess running the 2 audio amplifiers I have and the 500w inverter. Most of the time the inverter will probably not be used, so you could probably take that off there.
Temperature is a big thing too. If you run those wires in the engine compartment or near exhaust, your voltage drop will rise rapidly with a low-strand count wire.
Overkill probably, but better to be more robust here than to have the electrical system fail me at some point. I never even accounted for duty cycle. I assumed 100%, which is almost unheard of. The audio amps, while rated at 350w and 500w respectivly, will not pull that continously. You can overload a wire temporarily too, OEM's do it all the time. Look at the puny 16ga wire they use for your wiper circuit. urn those on on a 10degree day with some snow load on there and that motor will well exceed the 22 amps the 16ga can take 100% of the time. But after a few wipes, the load drops or the circuit breaker will blow. Look under the hood of a new car these days, there's alot more auto-reset circuit breakers than there used to be, so OEM's can run smaller wire (saving $$$) and still be safe about it.
Anyhow, I think I got off the original point here, which is, not all 2awg wire is created equal. There are differences, huge differences.
No, there is no terrestrial signal around here, my radio has seperate sat/ter signal meters, and confirmed, no ter signal. All sky. I dunno 
what sky, but the signal is there. 
For the average person, normal strand count wire works just fine, as does chassis/frame grounds when applied properly.
