Amplifier power needed by 1.7s

I think your room size (20x30) stretches the intended volume for 1.7s. The Cronus Magnum IS a great fit for this speaker. The Absolute Sound used that amp to review the Maggie 1.7 and came away all aglow. I told my audiobuddy (who owns 1.7s) about the Rogue Cronus Magnum, he bought one and absolutely loves the pairing.

Since you are listening at 11', the Cronus Magnum may be enough, but you may want to add some subs to flesh out that 4800 cu. ft. space. My audio buddy matched these SVS subs to his 1.7s and likes the combo very much.

Somehow (in my first response) I missed that you already have a REL sub. Everything I've read (and heard 1st hand from an owner of 1.7s and a Rogue Cronus Magnum indicates that that is an excellent amp/speaker match. After that, add a second matching REL sub. Two subs blend easier and give you more options for smoothing out room node resonances.

My experience with twin subs matches Auralone's. I started with a single sub in November with my 2-channel system with Mirage speakers. Three weeks later I added a second. Adding the second one unexpectedly resulted in much more 3-dimensional imaging and more perceived space around the voices and instruments.