PRX418S

So I bought a pair of new PRX418S subs and compaired to my JRX 218S's the JRX's give me way more thump! I am running the JRX218's each from Carvin HD1500 amps bridged at 900 watts each. The PRX418S's are each running off Samson SX2400 power amps bridged at 1500 watts per sub. The old JRX's give me way more thump. THe PRX418's just sound muddy... I cross over at about 80 - 100 on the JRX.s and Have tried several crossover points for the PRX's starting with the factory suggested 80htz. When I use the SRX subs I also pair them with a pair of SRX 815's powered with a new Peavey IPR 7500... I have tried different amps and have setteled on the old boat anchors because I just hate the new class D amps! They just dont give the push that old amps push! So my question is how do I get the THUMP out of the new PRX418's??? BTW Grateful Dead Jam Band using a mackie prov2 with onboard EQ...