You could use the larger 50 amp I think ac alt, run a spare 10 gauge wire from output stud to battery positive, with fuse or fuse link,and hook your amp there. Use a good battery, and never let it get old and you will be fine. You should also install a cheap voltmeter as the ammeter will no longer be accurate. $2 on ebay. If you need more switch to a single wire 100-200 amp alt and 2 gauge ground and positive wire.