Power Amp Doubling Output at 4 Ohm

Simply put, if everything else is equal an amplifier that can double power into 4 ohms compared to 8 ohms can supply more current to the speaker than one that cannot double power. Lower speaker impedances require more current, everything else being equal.

Of course, along the lines of Stan's comment, everything else is rarely equal.

On the question of maintaining tonal balance with "difficult" speaker loads, see my post dated yesterday (Sept. 8) in this thread.

Regards,
-- Al

The Pass Labs, which doubles power as impedance is halved produces better tonal balance and bass control, than did the NuForce amp, which has a significantly lower output impedance.

TVAD -- I'm sure that your observations were accurate, at least with the speakers you were using.

But once the output impedance gets below an order of magnitude less than the minimum impedance of the speaker (perhaps by a factor of 10 or so), it stands to reason that further improvements in that parameter would be far outweighed by other differences between the amplifiers. And in this case you are comparing a pure Class A amplifier (weighing 75 pounds per channel) with a Class D amplifier (weighing 8 pounds per channel), so there are certainly a great many other differences.

Also, keep in mind that once the output impedance gets below a certain point, it will be overshadowed by the resistance and/or inductance of the speaker cables themselves.

A minor correction, btw: Damping factor 4000 = Output impedance 0.002 ohms, not 0.0002.

Best,
-- Al