I don't mean to look down on your system (it's very nice for the money it cost);.... however;.... in my experience Rotel while really great stuff for the money it costs, is not really refined enough to notice any big changes from tweeks of any kind. Maybe a little....
So for that reason, I am not surprised at all that you did not notice any improvement from adding a Gray 400. The same will go for power cords. Get some hospital grade 14 awg cords to replace the 18 awg cord that came with the units. You will be fine. You will likely find them at your local electrical supply store for $10 to $20.
If you have a decent television, plug that TV into the Gray and the picture will shine...
So for that reason, I am not surprised at all that you did not notice any improvement from adding a Gray 400. The same will go for power cords. Get some hospital grade 14 awg cords to replace the 18 awg cord that came with the units. You will be fine. You will likely find them at your local electrical supply store for $10 to $20.
If you have a decent television, plug that TV into the Gray and the picture will shine...