I read your last thread so i know a bit about what your trying to do with the computer/reciever,it would help alot if you would list what reciever you have along with the model number plus a budget that you have to get this done.
Correct me if im wrong but the way it looks is that your just trying to use things that are laying around the house to get this treadmill system together which there is nothing wrong with doing that just dont expect too much.
I looked at the amp in the link & to run a 6.5 inch koss "subwoofer" it would be ok but in all honesty that amp is a mess,keep in mind that if you do buy that amp it will not be very good at all for car audio applications making it useless should you ever want to use it for something else,my experience with trinkets like that amp is that they end up in a closet till they get tossed out.
With the cost of the amp plus shipping & the cost of a power converter to drop your 110 volt down to 12 volt your easily looking at $70 or better,for that amount you could buy a real home audio amp(used) & not have to rig anything up.