What budget does he have? Does he want discrete sub outputs or can he go with a splitter. Not many programs have any material for two separate subs so a splitter works pretty well usually. The polk need at least 150 watts but will benefit from the subs. Does he lean towards separates or a receiver? Blue tooth input can be had in some models. The Marantz 5005 could work well in a 5.1 setup especially if you bi-amp the mains with two channels each. The mains can use up to 300 watts so maybe a receiver won't cut it but the 5005 is on sale with free shipping.