Amperage 2 vs 4 channels amplifier

I would ignore those specs altogether. Amplifier current ratings are among the most useless of specs, IMO, as they almost always represent how much current the amplifier (or in some cases just its power supply by itself) can supply into a dead short (zero ohms) for an unspecified tiny fraction of a second. Consider the following:

60 amperes into 2 ohms corresponds to 7200 watts
60 amperes into 4 ohms corresponds to 14400 watts
60 amperes into 8 ohms corresponds to 28800 watts
120 amperes into 2 ohms corresponds to 28800 watts
120 amperes into 4 ohms corresponds to 57600 watts
120 amperes into 8 ohms corresponds to 115200 watts

So obviously those amounts of current are never supplied into real-world speakers.

For further discussion of this see the following thread:

https://forum.audiogon.com/discussions/current-limit-onset-definition

Regards,
-- Al

What Al said: ignore.

Although an amplifier max current rating doesn't represent anything useful, however, if two amplifier both rated 100watt/channel, one max current rated 50A and the other one rated 30A, we can assume that the 50A rated one has a beefier power supply.