Connecting dual subs with speakon connectors

Red and yellow (together) to + / black to – on each channel on the power amp.

+1 @noromance 

That is Rel's way of hookup  But he better make sure that the red & yellow are both positive for his B&K's. I'd think so but but i never underestimate the marketing depts ability to make a different color as - such as yellow. Marketing can then say that the yellow wire is more appropriate for ground due to its molecular proclivities towards the negative side This would obviously be better that the way abc-xyz does it which tends to  slow the signals and therefore blur the VooDoo dust to the point of human incapacitation.

@ghdprentice  the high level input is the reconended input for this subwoofer.

@ditusa thank you very much. Sadly the manual has no mention of how to connect two subwoofers...

@noromance ​​​+ @artemus_5 : Thank you very much, I think this is what I was looking for. This makes a lot if sense as the yellow and red wires go to the two positive (red) speaker outputs when connecting one subwoofer. Just to clarify, I would connect one subwoofer with red and yellow to the positive speaker out of the left channel and black to the negative speaker out of the left channel and the other subwoofer with red and yellow to the positive speaker out of th right channel and black to the negative speaker out of the right channel?

Thank you very much for your help!

Yes

R*L = +    f L channel

B  =   ---       

Hook one to L, The other to R. Good to go. You may have to float your black IF you get a hum.              

• No problem. Just twist the same colors (from both subs) together and connect as the manual describes (for a single sub). I am running 2 subs this way. Works perfectly.