Parasound A21 with JDR Capri II

I have the Jeff Rowland Capri MKII and 201 mono blocks driving Sonus Faber Liuto Towers, but the 201's seem to run out of lungs when turned up a bit.

Been think of going back to class A or AB amp, I'm looking at the Parasound A21 which is class AB. Has anyone tried a Jeff Rowland preamp driving a Parasound amp?

If so, I would love to hear your comments and thoughts.

Many Thanks