hi lo input ajustement

Hi i was wondering if anybody know how to make a ajustable h-low input signal? Explanation i installed subwoofers on my CLS500 with the hi-lo input on my amplifier, but i was wondering if there a way to put some sort of potentionemeter, on the signal to have some sort of bass ajustment in the front ?   like what you put on RCA but a would like something for hi-low signal ?

Any help would be great

Thanks for the fast responce.. but my complete set up uses hi input on amplifier.  so i would have to change the hole set up to low input(RCA's) to install the LC-2.  I was maybe thinking of an l-pad... but i would prefer something allready made

Thanks