Hello,
I like all of the ideas above. I am wondering if you can accomplish your goal with some different speaker wire. I am going to suggest Straightwire speaker cables.
specifically the Expessivo II or the bigger Expressivo Grande II. You will be amazed at what these cables can do for your system. You get to keep your setup but just change the cables. Just so you know when KEF is demoed at shows they use Straightwire cables. They go together perfectly. You can keep the speakers you live but change and probably improve the sound quite a bit. Plus, these cables are so universal you can put them on almost any speaker. If you are in the Chicagoland area this store I buy gear from is a KEF and Straightwire dealer.
holmaudio.com
Also, you might want to look into the power cables. Straightwire has a Grey Lightning or Black Thunder power cable that won’t break the bank but really optimizes your gear. A different approach than changing from the LS50 to Harbeth speakers. I hope this helps.