The Paramount is listed at 16Hz/-3dB for small signals. Full power bandwidth is more like 30Hz.
I haven't looked at the distortion performance below those frequencies - I don't see the musical relevance - but if you need to go lower you probably need a solid-state amp.
I've tried several amps for my modified K15 bass bins. The best was a McIntosh 275. Until I tried a Bedini25. Glorious bass. But of course these use 97dB efficient drivers.