It seems the Edifier is interfering with my wifi - even though I got paranoid and switched its Bluetooth off. Before anyone thinks I'm crazy, I just contacted my internet service support. It worked for a while, then my wifi slowed down again after a few minutes. Tried different router settings too.
Plugged my MM-1s back in, after resetting my router, and now all is fine.
This is a real shame, as the Edifier e25HD sounded brilliant. Too good in fact that it was a bit harder for me to work - it has no tone controls but I could hear the DSP working at lower volumes. And they looked good enough to eat.
Can someone help me though? I have a single band router - will a dual band have helped? I can take this to the PC forum instead if anyone wants to help.