Upgrade amp or speakers?

This is a question that no one else can answer. If you are ENTIRELY happy with the speakers then you can change the amp, the sound will probably be different but there is no guarantee you will like it better. The speakers will make much more difference so if you are even considering changing them you should start there. Very often tuning the system with suspension devices, new cables or room sound treatments will make more difference than changing out amplification or sometimes even speakers. Remember that components of equal high quality may sound quite different and until you identify in your own mind exactly the qualities you value most you will be on a never ending search.

I would definately sell the Martin Logans and keep the amp. A friend of mine owned Martin Logans and he much prefered the sound of my large efficient horn loaded speakers. Also these are the type of speakers (very revealing & efficient) that sound good with the slightly warm sound of Classe.

Unless you are in love with the electrostatic sound, you might consider a quality pair of moving coil speakers and stay with your electronics. You might use a variety of footers to "tune" the sound of the system from there until you hit the sound you are looking for. I have had great results from a combination of Black Diamond Racing puck/cones and heavy brass Mapleshade footers.