Haha, i bet those speakers wont need a subwoofer 
I'm using my Mar-Kel70 for everything from jazz to heavy metal. For jazz i miss the little extra punch in the bass for some songs. And with Audioslave but my old Dynavoice speakers (with two 6.5" subs per speaker) didn't do it well without a subwoofer either
So, double the amount of drivers. Put them in a much bigger enclosure which is a backloaded horn. Should be enough bass and SPL
I'm using my Mar-Kel70 for everything from jazz to heavy metal. For jazz i miss the little extra punch in the bass for some songs. And with Audioslave but my old Dynavoice speakers (with two 6.5" subs per speaker) didn't do it well without a subwoofer either
So, double the amount of drivers. Put them in a much bigger enclosure which is a backloaded horn. Should be enough bass and SPL