$1500 to spend...

Yes the Marantz has a refined/relaxed sound. I'm most familiar with the PM-11S2, Heard a demo(about 8 years ago) with a Paradigm Signature 8 and could not believe the quality of the midrange and the overall liquidity. A wide variety of music was demoed and it was not lacking in bass maybe the large Paradigms had the perfect synergy? Had I not already recently purchased a Valve Audio Predator I would have purchased that amp. The newer 11S3 is claimed to have a better power supply so it might have more grunt/bite, I would avoid the 11S1 due to age. Krell is another(180 degree)different option the 400ix and the 300il would give you all the power and bass you would need but not as refined(liquid) as the Marantz. Avoid the Chinese made Krell S series amps known to have QC problems. If you asked which amp I would choose it would be between the Marantz PM 11S3 or Krell 400ix the condition and price would be the deciding factor both are great amps!

Once one identifies the sonic experience one is looking(hearing) for it is the combination of speaker and amplifier that will provide it.

Just to update here - I picked up Herbies gliders for my speakers and they changed the game.  Unbelievable how much they cleaned up my bloaty bass problem.  Also picked up a second-hand Rogue Sphinx and currently on the Tube merry-go-round.  Not sure if I like it better than the Brio-R.... We'll see.

Well, The gliders removed the drawback of the speakers, you liked the sound with the Brio, and now have a different amplifier to compare and with the option of tube rolling and provision of more power. Let us know the result, thanks.  

IMHO, your biggest bang for the buck upgrade would be room treatments.