I’m a fan of Martin Logan speakers so naturally I’m biased. ツ
I was initially drawn to the ElectroMotion ESL line but once I heard the Spires, I was hooked.
I have two amps I interchange. One is a pair of highly modified Golden Tube Audio SE-40 75W tube monoblocks and the other is a pair of modded 600W pro audio solid state monoblocks.
The two amps sound very different. The tube amp is sweet and mellow while the s/s amps have an incredible slam that just isn’t there with the tubes. Rock and large orchestral music really come alive with the s/s amps, while jazz, vocal, small chamber ensembles and instrumental sound divine with the tubes.
Depending on your taste in music, you may really like the ESL speakers with your McIntosh gear or not.
As for cables, I’m a believer but recognize that not everyone else is. I’d recommend you start with decent mid-priced cables (e.g. Nordost Blue Heaven, Blue Jeans, etc.). Once you are familiar with the sound of your system, audition a higher end cable. There are lots of companies that offer a no questions asked, money back guarantee.
I am a fan of Teo Audio Game Changer cables. At ~$600 they aren’t exactly cheap but in MY system they made a significant improvement. YMMV.
And finally, give some consideration to room treatments. A room can make or break a system.