Could i hook up my orion d5000 without a ho alt.? If I just wanted to run one sub, would that be ok? I know it won't push it's potential, but will it hurt the amp?
those amps like about 200amps each at optimal ohm load for max power... at a higher ohm load, you should be ok, with only a 100-150 amp pull of current.
yes, to answer your questions lack of current, will make internal parts of the amps, to over heat. Example ics, chips, transistors, etc... all these can heat up solder points in the board, and stuff can eventually shake loose. if you feel the chips on the board itself, with proper current, you will still see how hot they get under proper operation!