Typically the subwoofer pre-outs do not carry any high frequency sounds. My Kenwood allows me to choose the frequency cutoff, i imagine your deck probably does too. It is fine to wire it as you suggested. Just be aware that you might not get a lot of sound out of the subs, I don't, but then again I really never did. They work, I can feel the vibrations on the back wall, I just can't really hear much from them.