There is debate among audiophiles surrounding the impact that high-end cables have on audio systems with audibility of the changes central to the discussion. While some speaker wire marketers claim audible improvement with design or exotic materials, skeptics say that a few meters of speaker wire from the power amplifier to the binding posts of the loudspeakers cannot possibly have much influence because of the greater influence from complex crossover circuits found in most speakers and particularly from the speaker driver voice coils that have several meters of very thin wire. To justify claims of enhanced audio quality, many marketers of high-end speaker cables cite electrical properties such as skin effect, characteristic impedance or resonance; properties which are generally little understood by consumers. None of these have any measurable effect at audio frequencies, though each matters at radio frequencies. Industry experts have disproven the higher quality claims through measurement of the sound systems and through double-blind ABX tests of listeners. There is however agreement that the overall resistance of the speaker wire should not be too high. As well, the observed problems with speaker cable quality are largest for loudspeakers with passive cross-overs such as those typical of home stereos.