Example: 4V@80ohms vs. 4V@100ohms

Which is technically better? I'm confused as to which has a stronger signal... my instinct says the latter.

Is there some kind of trade off between signal strength and how much the output is affected? (this part might not make sense so read the following article I found) Maybe someone can explain this to me.

Quote:
Output Impedance:
Some head units (or other devices that have an audio output signal) rate the output impedance of their pre-amp lines. These specs will tell you how robust the output signal is. Since all decks have more than a zero output impedance (50-500 ohms) and all other devices have something less than an infinite input impedance (10,000-100,000 ohms), the input circuit will affect the signal from the previous piece of audio equipment. A lower output impedance (50 ohms) will be affected less than one with a higher output impedance (500 ohms). The most common (and least degrading) effect on the signal is the slight reduction in the signal level. This slight reduction is generally never noticed and is completely normal. A bigger problem appears when some piece of equipment does not have a purely resistive input circuit. This is generally from a ultrasonic filter on the input. These will cause the high frequency part of the signal to be attenuated more than the rest of the signal. Equipment with higher output impedances will have more high frequency roll off than those with a lower output impedance.

TIA

 

Higher output voltage is better.

An output voltage at a higher resistance is going to be less than at a lower resistance. For instance, if you run your sub amp at 4 ohms, you'll make X amount of power. At 2 ohms you'll make X*1.5.

So yeah, the one on the right is more power.