I had contemplated using longer runs of my Romex return wires and running them directly to my panels ground wire, not hard to do as my panel is in my listening room.No, once again I strongly recommend against doing that. What happens when the speaker wires are disconnected from the amplifier has no relevance to what I am saying.
This way all grunge would bypass the amplification chain and go right to ground at the panel.
My amp will not self destruct if the speaker wires are disconnected.
If I feel brave in the near future I may try this experiment ...
Keep in mind that electric current only flows if there is a complete circuit, from the source to the load and back to the source (the amplifier being the source, in this context). The same amount of current that goes out to the load needs to (and will) come back to the source, regardless of whatever grunge may be riding on it.
In the situation you are considering, the complete circuit would be from the + terminal of the amp to the + terminal of the speaker, then from the - terminal of the speaker to the ground at the panel, then through the AC safety ground wiring to the system, and then via unpredictable paths through the system to the circuit ground of the amp.
If the amp has its AC safety ground and its circuit ground connected directly together, that would be the path the return current would take. What that would amount to is connecting the AC safety ground wiring between the amp and the panel, as well as the wiring from the speaker to the panel, in between (in series with) the connection of the amp to the speaker. At best, that will degrade sonics considerably. But the effects may be much worse than that.
If the amp connects its AC safety ground to its circuit ground via a passive component (a resistor, inductor, or capacitor), and some other component in the system has its circuit ground and AC safety ground connected directly together, or connected together via a lower impedance than in the amp, then most of the return current would find its way back to the amp via that or those other components and their interconnections. Which could very conceivably result in oscillations and/or damage, as I previously indicated.
Regards,
-- Al