The bass is unlikely to sound like a crack with wires that are too small. What happens is that the resistance of the wire will reduce the power slightly, but probably not enough to really hear the difference. But they may heat up due to the current.
To be realistic rather than opinionated, consider that the resistance of, say 18 guage wire 20 feet long is .05 ohms. Say 14 guage wire is .012 ohms. The speaker is 4 ohms. The total resistance of the 18 guage set up is therefore 4.05 ohms, and the 14 guage set up is 4.012 ohms. So, the actual percentage difference is pretty slight, and so the actual decrease in power is a very very small percentage, just do the math.
Good luck hearing the difference, except subjectively. In a double blind test, I would say few could tell.
But lots of current will heat up wire in proportion to the wire guage, and even 10 guage wire will warm up slightly, and the higher number guage, the more it will heat up. In fact, home fuses are determined by how much current the wire will handle without heating up very much, certainly not enough to melt the conductor!
And to say speakers are "current driven" is a curious theory, likely picked up in casual conversation with people who use terms like that without really understanding electronics. Speakers are POWER driven, a combination of watts and volts. That is, a speaker will be just as loud with 1 amp and 10 volts as with 10 amps and 1 volt. The actual power is the same. But the speaker with the lower current will have a slightly better damping factor.
Check it out.
The main reason for all these low impedance systems is the effort to gain loudness via power with the limitations of 12 volts. Loudness at the expense of quality. If we had 120 volts in a car, we would have lots of powser available even at 8 ohms, but we don't. And its a LOT cheaper to build an amp to put out 1000 watts at i ohm than to build an amp which will put out 1000 watts at 8 ohms or even 4 ohms. The marketing of car equipment is on a power craze which encourages design quality compromises, sad to say.
And I am a power lover, actually. As I said, I have about 6000 total watts in my home system and I was the person who, with Bob Carver, built the world's first super amp, a huge tube amp, in 1966, from which design, Bob subsequently made a transistor version, the Phase LInear 700, which put out about 725 watts rms The largest previous stereo amp was the McIntosh 275, which was 150 watts rms. That Phase LInear started the movement to power. Heady days! So, now I have the Sunfire Signature 7 channel amp and an 18" Velodyne subwoofer. Sure would like to try that amp in a car with a good inverter!
