You’ve got the best sounding of all the Watt/Puppy version there in the 7’s. My friend who has been through them all, even the 8’s came back to the 7’s.
datsawman
Watt Puppy 7 needs new or used Amp and Pre-amp
Although they are 90db efficient and only need a 50watts or more to get loud, they are a nasty load for an amp in the bass, nearly 2ohm and 34 degrees -phase shift.
https://www.stereophile.com/images/archivesart/Wilfig1.jpg
Which means to get the "very best bass performace" out of them, you need an amp that can do "good current" "almost" doubling wattage down into 2ohms and be happy doing it continuously.
This means good linear amps and solid state, preferably using bi-polar (bjt) output stages (mosfets at a pinch). Your vintage Marantz is not one of these, neither are tube or Class-D amps. Music Reference RM200 are a tube exception with their 2ohm tap, but wattage then maybe very low for partying
If you want the best and need some help to get some ideas from the technical members here here on what I’ve outlined above just ask and they will help out with more suggestions
Cheers George