that 52x4= max wattage

that deck is more like 15x4 RMS
even if the box says 20rms its really more like 15...and with that said its a very dirty 15...

pushing type R's with that deck alone will sound like a nightmare. under powering those speakers will be a horrible idea...get a 4 channel amp trust me...

i think that deck only has one set pf pre-outs so you would have to get a RCA splitter... you will loose fade but should still keep balance.

i say ( if you can afford it, if not ignore this) get a better deck.