$8k for speakers - new or used

What type "punch" are you looking for?  Chest hitting bass, bass that you feel on your bottom while sitting on the couch, or quick and taut bass.  I'm learning more "punch" means different to some.   If it's the first 2 I described you are looking for, getting a sub would be the place to upgrade to.  If you are looking to get another pair of speaekrs, I'd recommend NSMT.  I'm a big fan of this line lately.  I'm really liking my NSMT 100's.  They have active bandpass so I have the "punch" (quick/taut/solid) bass I'm looking for.   I've just moved to them from using Magnepan 1.6's for 18yrs and couldn't be happier.  If you can strecth the budget, I'd recommend the Clairvoyant's with 15EXP or System One.

All, I appreciate the great feedback

Get a couple subs.  Once set up you will have better sounding main speakers as well.

I think 804d3 should have tons of detail and bass punch.

But if you just have the bug, in the 8k range, I’d look at Perlisten R7T towers. Borresen X3, or Dynaudio contour 60i. Or a pair of 805d4 and a Perlisten Sub.

Also consider mofi source point 888, and Q acoustics concept 500.