I'm going to disagree on the monoblock idea. I think bi-amping improves MLs a lot. Speaker cables--definitely change them. I'm not big on the networked versions. You have matching amps, so vertically bi-amping with very short runs of quality speaker cable would improve things. Spikes--absolutely--get them from ML directly.
Another tip: you can build a resistor for the power into the MLs. I have done this with a simple 125 volt radioshack 2k pot. I reduce the voltage to the ESL panels, they run higher than they should on my monoliths. I have not done this with SL3s, but it could tame some of the harshness.
Lastly, don't expect the SL3's to do BIG recordings (full orchestra--etc) as well as they do vocals, small jazz groups, and chamber music. They really excell in these areas and because of this you will notice they sound muddy in comparison when playing larger scale music.
Another tip: you can build a resistor for the power into the MLs. I have done this with a simple 125 volt radioshack 2k pot. I reduce the voltage to the ESL panels, they run higher than they should on my monoliths. I have not done this with SL3s, but it could tame some of the harshness.
Lastly, don't expect the SL3's to do BIG recordings (full orchestra--etc) as well as they do vocals, small jazz groups, and chamber music. They really excell in these areas and because of this you will notice they sound muddy in comparison when playing larger scale music.