In fact, Anthony Gallo's Reference SA amp is an unfairly overlooked perfect solution for such applications, sporting a 40-200Hz adjustable low-pass filter, dual-mono level controls, dual-mono phase controls, 160/250 watts x 2 into 8/4 ohms or 450/650 x 1.and bass EQ from -3dB to +6dB. it is a crafty machine perfectly suited to power for example my Zu Audio Definition Pro bass arrays without a separ