Do I need a sub woofer to match my ATC SCM11s

Thanks for the suggestion. Has to be that big and expensive? Does it make more sense to sell the ATCs and get floor standing speakers? Any suggestions of good speakers that work well with the Hegel H160? I'm look for a wider and deeper soundstage. Right now it sounds too thin to me, if that makes sense?  I'm open to either solution. 

JL D108 would be another option. Unfortunately great subwoofers aren’t cheap. 

A subwoofer is not a panacea to that thin sound that you describe. You should check out a Spendor floor stander. They have a footprint the same size as a stand mount.
https://store.acousticsounds.com/index.cfm?get=results&searchtext=spendor

if you love your speakers, ATC makes great passive and active floor standers...

and the e110 is not that big...one just went for $875 used...