What does High Current mean?

Actually the math does work. A constant voltage source would double the power delivered to the load each time you halve the resistance.

Power = Voltage squared divided by resistance (P=EE/R), so if we halve the resistance:

EE/((1/2)R)=2(EE/R)=2P, or twice the power.

It is difficult (i.e. expensive) to build an amp that functions as a constant voltage source. Many amps fall off the curve as impedance drops below 4 ohms.

If the Sim Audio amp operated as a constant voltage source it would generate 380 watts into 4 ohms, 760 watts into 2 ohms, and 1520 watts into 1 ohm.

The YBA does follow the doubling and operates as a constant voltage source down to 1 ohm.

So what does this mean? It tells you how to match the amp with a speaker. The YBA can handle a load that drops to 1 ohm over part of the frequency range, if 80 watts at 8 ohms is enough for sufficient volume.

The Sim Audio amp provides more power at 8 ohms, but may have trouble with difficult loads whose impedances dip below 4 ohms.

Check the impedance vs frequency curve for the intended speaker.

A beautifully clear and succinct explanation, Ghostrider45.

This is seldom emphasized or explained well by reviewers. What we frequently hear instead -- often from sellers -- is, "this amp is much more powerful than it's output rating suggests," or words to that effect. Unfortunately, few readers or prospective buyers seem to believe the claim.

But, I know from personal experience that the statement can be amazingly true when you have a very difficult, low impedance speaker to drive and can use a well-designed, well-made amp that doubles down all the way to 1 or 2 ohms. A seemingly insignificant output at 8 ohms can easily translate to BIG output at 2 ohms if it's the right amp. Surprised the heck out of me!