I do agree with at least a pair of subs, but @russ69 brings up a great point by upgrading to complimenting preamp. There are many to choose from. First thing you’ll need to figure out is budget. From the subs you are looking at, I’m guessing you have a healthy budget?
My upgrade
I started this quest several years ago. I started with acquiring a Linn Majik DSM, Martin Logan ESL 11A's, I used the Linn as a streamer, Dan and amp and was fairly happy. I also use Kimber Kable speaker wires. I eventually added a Peachtree Nova 300 amp. I used the Linn as a steamer and line source and was a little happier. I added a Parasound JC5 today and am blown away with the sound I am getting. The Linn is now my streamer, dac, and preamp. I will be keeping this amp but am wondering where do I go from here. I'm playing with the idea of a pair of subs either Martin Logan Balanceforce 210's or a pair of REL's advice please