Fairly easy, ill try and put it in steps as best i can.
1. Remove the plastic piece on the floor at the back, or at least a couple screws in it so youl be able to remove the interior panel.
2. Youl have to remove all the plastic pegs that hold the panel in, this is pretty easy either if you have the upholstry removal tool, or even a flat head (common slot) screw driver and a pair of needle nose pliers. Be carefull and you wont break any, usually you can just pry a bit with the screwdriver, then when its out enough you can use the needle nose pliers to safely pry out further. There are also two screws that need to be removed while your at this.
3. Next you need to take out the rest of the screws holding it down, there are about 3 that hold it to the floor, and they are easily accessable by pulling up the carpet a bit, the carpet can just slide right back in when you put it back together.
4. At this point if you simply want to remove the amp you can probably just pull the panel a bit and be able to get to it, but if you cant, heres the rest.
Now this is were things get a bit more complicated from here on. You need a torx bit for the seat belt to come out. Its very easy to access, just pull at the top of the plastic cover and it should unclip and fold down.
5. This step also sucks, because theres this tiny bolt, and a tiny space to get to it. I cannot remember what sized socket works for this, however this bolt should be taken out if possible. Im unsure if perhaps you can do with without removing the bolt.
6. And this is easy as it gets, the last step basically. Theres one little thing that might still be holding it, and all you have to do is pull it up

. Once this is done i find a way that works for me to take it out is to take it from the top and basically slide it out. You can pull the top down a bit while pulling it up from the bottom, im sure youl figure it out, or else youl probably have to remove the little metal flap thing that goes behind the seats. Theres no real need to have the panel entirely out, you can leave the seatbelt housing thing still in there if you want and just put the panel to the front (did i mention the seats should probably be folded down?). And heres a pic of the begining part of this step.
Putting it back together is simple, pretty much the reverse. You will probably figure out easier ways to get at it.
Good luck!