To make a passive HP filter.
Your Mac has a steady fixed input impedance of 20k, using this you could do a simple 1st order filter with just one component (a capacitor) on this by putting a
0.068uf cap in series with the input, that will roll off the bass a 117hz -3db.
or a 0.1uf will be 80hz -3db
or a 0.033uf will be 240hz -3db.
or 0.082uf will be 97hz -3db
Or using the 20kohm input you can work out more complex and steeper 2nd order, 3rd or 4th.