Take some time and learn this firsthand. If you have a meter or access to it, meter your resistance and find out what it is. Remember that electricity is an algebra equation, what you do to one side you must do to the other. It is not about the amount of metal in the chassis, it is about the resistance that current has flowing through this metal and all the crappy welds, glued together unibody seams and small guage ground wires that they use at the factory. There is a reason for the BIG 3 and if you think about it you are already started on ensuring that the ground return has as low a resistance as possible by upgrading the grounds as the BIG 3 wants you to do. All this does is complete the process and a good shop will always take this vital step to ensure that their job is done properly.
A high ground return resistance can be a major cause of noise, excessive heat buildup, low power output (as was found out above) and eventual failure of the power supply section of the amp.
A high ground return resistance can be a major cause of noise, excessive heat buildup, low power output (as was found out above) and eventual failure of the power supply section of the amp.
