Does the CA300 have a switch for selecting RCA and balanced. If so, it should be selected to balanced if you are using balanced cables. If you are using RCA cable, make sure that pins 1 and 3 of the CA300 XLR connecotrs are shorted oterwise you may have some humming and other nosie problems.
Also on the EAD RCA-XLR adaptor, pins 1 and 3 should be shorted together.
Good luck.
Also on the EAD RCA-XLR adaptor, pins 1 and 3 should be shorted together.
Good luck.