It's my humble opinion that this
is a bug, and an annoying one at that. The empeg team is aware of it (well, it's been reported to the bug list).
The reason this behavior is there, is because there's no volume knob on the Mark1 players. The left/right buttons do adjust the volume on the Mark1 units. Some special-case coding needs to be done in that area of the code so that Mk1s and Mk2s both work correctly.
Note that this bug extends to the remote control for both the Mark1 and Mark2 player. The remote has separate controls for volume and track. But if you use the volume controls, then the track controls start changing the volume afterwards.
It is my greatest hope that this bug will be corrected before 1.1 goes final. I don't know if it will, though.
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Tony Fabris