Bought a pair Eris E5, and saw it has a three-prong mains-connection,
whereas the Eris E4.5 has a 2-prong mains connection (double isolated).
Realizing it'd be best for safety to use a grounded mains outlet for the E5, there are however locations where no such outlets are available, and/or improvising a ground connection not convenient.
So I'm wondering: is using a grounded mains outlet a hard (safety) requirement for the E5 ?
(The 'comparable' E4.5 is able to do without)