In the original Paramour (that goes back a ways!) the C7-X is a plate choke, not a power supply choke. It's 10 henries, which is on the small side. More inductance will make a big improvement in the bass, but works best with a larger and more optimized output transformer. Back in the day, we had an upgrade kit with a higher-inductance choke and an upgrade transformer, which is no longer available.
I believe Magnequest still has a candidate set, and we have since then developed our own iron which is used in the Stereomour and S.E.X. amps. I'll link it below. Unfortunately I don't think there are detailed instructions on making the mod, but I believe it's been done by some.
This is a little complicated, but if one of these ideas interests you we can talk further.