Good to see you back here, Herman.
Not sure that I agree with you, though, regarding:
BTW despite what Ralph contends phono cartridges are NOT balanced as there is no ground, no ground pin connection, only 2 lines out.
All sound sources are single ended, compressions and refractions.
When you get to the speaker they are all single ended, they move in and out, no balance.
It is true, of course, that when a cartridge is not connected to anything its output is "floating" with respect to whatever ground reference one may choose to define. However if the two output lines of the cartridge are connected to a properly balanced input of a phono stage, both the impedances and the signal amplitudes of its two lines will be balanced with respect to the ground of that phono stage. In other words, the nature of a cartridge is such that connection of its output lines to a balanced input causes its output to become balanced.
The same goes for a speaker, when connected to a power amp having balanced outputs.
Compressions and refractions (I think that should be "rarefactions") that occur in the air as acoustic waves propagate are a different and unrelated matter, as I see it.
Regards,
-- Al