If serious noise reduction is an important goal look at using a CNC spindle instead.
I believe there’s been a few Maslovians that have used the smaller 400-500W brushed DC spindles popular with the X Carvers, but I lean towards the 800 to 1500W VFD controlled ones. More power Scottie! There’s been discussions of water vs air cooled on cnczone.com (and elsewhere, giggle, duckduckmoose^^^^^go, bingbang, etc). Water’s supposedly slightly quieter, air’s easier, supporters on both sides. Think I’d try air cooled first, less ice and algae.
Box in a router and any sound reduction will be made up by a big honking cooling fan - unless you count the dead silence of the uncooled smoking hulk before the fire engines arrive