well, within the range of the amplifier, I suppose. on paper, a 4 ohm load on a given amp may produce 100 watts, whereas a 2 ohm load would produce (theoretically) 200 watts. The 4 ohm load would leave more dynamic headroom for the amplifier, the amp would produce less THD, have a better signal to noise ratio, improved damping factor, and so forth. In reality? you'll not likely hear any difference. You just get more power from the amplifier with a lower load.
One way to keep distortion under control is using amplifiers that far exceed the power rating of the speakers being used, furthermore the amplifier will run cooler and last longer.
I recommend not to dismiss distortion (THD) figures altogether, The best way to know if distortion will bother you is listening your prospects and many alternatives BEFORE buying.
THD specs are very misleading, and on pretty much all modern amplifiers, THD is well below the level of human hearing perception. Also, you really can't hear audible distortion below about 10% with a subwoofer, and to be honest, the speakers produce more distortion by design, than the amplifier.. so THD in that regard really is a moot point.
Glasswolf, if you posted that in an audiophile forum probably hell would break loose.
If you swap a modern day Kicker with a modern day McIntosh in an otherwise high end setup many if not most SQ people will favor the latter easily and THD will surely be in the mix.
Theoretical arguments can't account for this.
Now for those who can't discern or care on the differences then there is lots of money to be saved!
Richard Clark proved that within proper operating parameters, you can't tell one amp from another. He proved this fifteen years ago with a $10,000 challenge, and nobody yet has collected on that.
The problem with basing anything on "THD" is that Total Harmonic Distortion can be measured a number of ways, none of which are usually specified by the manufacturer thus allowing them mto skew the results quite dramatically in their favor. Was the measurement taken using a sustained tone, or burst? Was it measured at full output? Was it measured using a single frequency tone, or a 20-20,000Hz white noise tone? Was it measured on one channel, or all channels simultadeously? What weighting was applied to the mwasurement? Get the idea? It's not a good number to use on which to base a purchase. Also, since car audio is 99.99% solid state amplifiers, and they are ALL in the 0.0xdBA or better THD range, it really is inaudible in a car. As I said, the speakers themselves produce far more distortion than the amplifier does, making the use of THD a moot point for judging an amplifier. "Audiophiles" also think they can hear the difference between two different pair of RCA cables. Another fallacy easily disproved in a simple blind test.
Just because I can show a slight variation on an oscilloscope in an electrical signal with 100Xamplification, that doesn't mean your ears are sensitive enough to hear that difference.
I am familiar with all those good arguments and I have seen people endlessly debating and collecting bitterness over them. Audio gear is made to enjoy music.
Me, I would take the kicker for a month and the McIntosh for another month and I would keep the one I liked better, assuming that the rest of my system would be high end.
As for quality specs, I would review them to get a notion of the type of product I am dealing with and to decide if I want to research further into it but *nothing more*. On the other hand I would always like to see them to complement other sources of information.