I have an Infinity 5761A 6 channel amp powering all four door speakers and a sub box. I've noticed that my left side front door speaker sounds blown when i play it at mid level and not as loud as my front right..ive also noticed that my left side hisses at low volumn, even when the stereo is off. So i thought at first my speaker was blown and swapped it out with the right side speaker and it worked fine on that side and the right side that origionally was fine on the right side sounded blown on the left.. And lastly..sometimes i sence looseing power to my fronts.. Is my amp blown?? its driving me crazy..any replys are appreciated..ty

 

Switch the right and left RCA's on your amp...So put the right RCA on the left input, and the left RCA on the right input.

Now, if the problem switched sides (hissing and what not on your right side now), you know its something with the RCA's or your HU.

Just the first thing I would try anyway, to rule some stuff out.

If it does switch sides, my first guess would be something with the RCA's...

 

So did you try what Bartak1 said?