for me it WAS both a and b

when I finally had time to troubleshoot I popped the hood and immediately saw the problem - the install shop had either failed to re-attach the negative to the battery post or had attached it loose so it came completely off. It was resting up against the post so the car would start, however whenever certain changes to the electrical system occurred, such as when the brake lights were on or when the cooling fans turned on, the empeg would go blank for a few seconds

now I can properly get back to drifting opposite lock around corners while heel and toeing, hitting the AC, and flashing the high beams without fear that the Initial D soundtrack will skip :P