1 channel blown on my amp?

[99grandprixGT 5,000+ posts]

i have an alpine 2 channel amp pushing my front 5.25 speakers. a couple days ago one started rattling. so i figured the speaker blew. so today i put another set in there and the same side dosnt work of a new speaker. so i switched the channel on the amp to the opposite speakers and now it works. the amp only has one gain knob so its the same for both channels so i thought it was weird that only one channel blew and not both, so i guess im asking if its possible for one only one channel to stop working? i dont understand why only one would blow if i did something wrong setting the gain. heres the amp

http://www.crutchfield.com/S-R7Sri1UZnQ9/App/Product/Item/Main.aspx?i=500MRPT220

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