I have a Processor with XLR balanced outputs and unbalanced RCA PRE_OUT outputs , all options to a subwoofer connection.
My subwoofer have only RCA In Input.
What is the best option to connect ?
Well @ronen the answer seems pretty obvious as you only have an unbalanced RCA connection common to both the subwoofer and your prepro.
Is there also an option to use XLR to RCA adaptor …?
Sure, but it might not sound better than unbalanced to unbalanced.
It might though.
There is no benefit to using a simple XLR to RCA adapter @aangen and @ronen. You only enjoy the common mode noise reduction benefit of balanced operation if both ends of the balanced interconnect are connected to a differential circuit. A work around which would retain a balanced connection’s benefits would be to obtain a single-ended to balanced transformer like this Iso Max unit which I’ve linked. You would run a long balanced interconnect from pre-pro to the Iso-max, sited immediately at the subwoofer. Then a short unbalanced interconnect from Iso-max to the sub.
Of course, this entire exercise wouldn’t be worth bothering with unless you have a long cable run between pre-pro and subwoofer. If you only have a 10 foot run you might as well just stick with a well shielded single-ended interconnect.
Paul posted a video on using xlr to rca adapters yesterday. You might want to listen to it: