I'm not talking about soldering aluminum.... Cut the aluminum bar to the correct length, drill 3 holes, attach lugs to the bare wires then connect all ground connections to the new bar at the center point. See attached picture which shows a later XL-600 amp. The aluminum ground bar that is shown on the capacitor bank is the factory installed ground bar in my amp, so even Hafler switched to a ground bar for all of their later models. Just about all modern amplifiers use either a piece of plate or a very large copper pour on a circuit board for the ground plane.
Sure the large gauge copper wire is more than adequate! The aluminum bar (I've used a copper bar too) is also more than adequate and looks much better IMO.
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