You know when you are dealing with a BS company....

Or they say that improvement should be based on price. The more expensive the component the better it sounds. And they ignore the reality of the effect of set up and synergy. They would lose money if they did, wouldn't they. :-)

@kraftwerkturbo

Many audiophiles fall victim to snake oil cables...forgetting or simply not acknowledging why cables are different/may sound different.

Metallurgy - silver is the best conductor of electricity. High purity copper with lots of .999s is fine too. If the manufacturer doesn’t make fantastical claims about improvements; but simply markets their cabile as "high-quality" I think it’s worth buying, provided of course, the cost is not thousands of dollars. Consider if you will, how much food --> Swiss Chalet, other electronics, etc. you can buy with that money instead??

When an amplifier is driving a reactive load (speakers) in this case, how well speakers conform to the damping factor can impact frequency response. Some so-called "high-end" cables have been known to act as antennas and pick up noise; and in turn, they adversely influence how the speakers respond when fed power, thus altering the frequency response you hear. It's not clarity or anything magical - it's just that certain frequencies have now been attenuated or accentuated.

In particular, I have found thin CCAW wire (thin-sounding) to be much interior to high purity copper or silver, regardless of AWG. Lower AWG just means less losses; even if we can’t discern them in a repeatable manner. Hearing the difference after days, weeks, months, or even hours is simply the brain working harder at filtering the sound you hear, since you are paying more attention.

While speaker cables can sound different, the idea of improving sound quality just because of the cable (rather than the inherent performance metrics of your audio components + speakers is silly. Cables should not alter the sound, they should get out of the way and allow your audio gear perform at an optimal level.

At the very least, I want 100% improvement with every higher level.

However, other companies, with good reputations, sell much higher priced cables and people are fine with it.  These companies have learned to manage the hype to sound realistic, perhaps even a big humble, focus on the quality build and make their claims more believable, and people spend way too much on cables.  (Don't interpret this to mean I don't believe or appreciate the tremendous improvement that quality cables make).

"You can expect a 15% to 20% improvement in sound for each level as you move up the line. 

I think you are misunderstanding what they are saying. I think they are saying that there is a 15-20% difference between each level of cable. Not a 15-20% improvement in your system sound but a 15-20% change in relation to the small change a cable makes. So 15-20% to the 1% change (SWAG) a cable makes.