I use a PJ5 (flats) and a 5 string Jazz (very old rounds) through an Aguilar TH500 with my Super Compact and the sound is as deep, fat and as warm as you could want. I found that I get a sound I like out of Markbass amps with the VLE and VPF switched off, but I've never played your amp.
This cab will only put out what you pit in, so IMO it's the amp and bass that's not getting your sound.