Thanks for your reply SirQuack! Sorry for this confusion, I was talking about the RCA cable that I needed to connect and re-connect to the 1/4 phone line in to be able to get the sub back to normal.
My EP350 V3 have the exact same back panel that is showed in the owners manual pdf file available on the Axiom site. If not using the high-level input, I think the only way to connect in is an RCA cable used with a 1/4 phone adapter (included in the box) into the sub. But it is also stated that, by removing the adapter (the one fixed into the back of the sub called 1/4” phone-to-RCA adaptor from the XLR input jack) someone could connect in with an XLR female cable.
to which my question : Would it be better to connect a RCA to XLR female cable into that input jack? and if yes, how do I remove that adaptor without damaging anything?
Sorry for the confusion....