[Roen]

I'm new to the audiophile game and trying to understand specs between devices.

So far, for three different devices, Max power output has been quoted differently.

Device 1: 105 mW @ 20 ohms, 100 mW @ 40 ohms, 40 mW @ 220 ohms
Device 2: 50 mW / ch @ 70 ohms
Device 3: 50 mW x 2

How can I make an apples to apples comparison between the 3?

 

[ClieOS]

Make a X-Y graph and put Device 1's load impedance as X and output power as Y, connect the three point and it will give you a very rough curve. You can use the curve to compare it to Device 2's spec. It won't be totally accurate, but at least it will give you some idea.
 
Device 3's spec is however completely useless, as it doesn't tell you want kind of load it used for the measurement.

 

[Speedskater]

Comparing specs from different manufactures (and sometimes different model lines) is just wheel spinning.
The measurements need to be done on the same test stand and conditions.
 
There was a blog a few years ago, about a receiver manufacture that used the same internal circuit in different model lines. Yep, each one had different specs.