PrimaLuna EVO 300

Any PrimaLuna EVO 300 owners out there experience very low bass? The voltage on the sub outs is so low that no sub would do anything unless maxed out. I'm now using stereo REL 212s, running line level, and that's provided adequate bass at about 60% gain. But I'm still surprised by how attenuated the deep lows are with my EVO 300. (By the way, I'm also using Cornwall IV loudspeakers, an Aurender A15 for digital, and Rega P6/Hana SL MC turntable/cart).