$8k for speakers - new or used

Try listening to some Wilson  Watt  Puppies - they might do the trick for you. They can be had used in that price range.

check out the monitor audio gold 200 G5 or the G6

You describe "wanting more - maybe detail, punch, bass." Have you considered keeping the B&W's and look into getting a quality subwoofer? You could buy a Rel No. 31 or 32, or a Martin Logan Balanced Force 212 with that budget.

https://rel.net/product-category/reference-series/

https://www.martinlogan.com/en/product/balancedforce-212

Opinions are like..... For my money, I'd ditch Macintosh because AFAIK all their gear is "warm" lacking detail. I'd go open baffle, Caladan, and if you want to better them, PureAudioProject, or the like. Caladans sound pretty bad for the first 300 hours or so, the capacitors are the biggest issue, but the bass drivers definitely improve as well, but they are punishingly bright at first, though perhaps not with a Mac preamp??? 

https://www.audiogon.com/listings/lisbad50-linkwitz-lab-orion-v2-full-range?refsource=hifishark