The VC takes to a bass shelf quite well.
If you don’t want to try EQ, have you tried the universe lambskin pads, yet? IIRC, they had the most low-end grunt.
Using an amplifier with a higher output impedance, like an OTL tube amp, can makes a noticeable improvement in sub bass quantity. This is the case with my Bottlehead Crackatwoa, as well as my vintage Sansui integrated amp.
You can also play around with different sources. For example, the higher-end Schiit DACs posses what’s known as “Moffat bass,” which could help lend a bit of extra authority.