You'll probably hear a wide range of inputs but my personal experience with my older Aerius i model ESLs is the more clean power they get the better they'll sound, especially their bass response. I drive mine with a pair of vintage McIntosh MC2200 amplifiers and they sound good to my ears. I occasionally switch to my other amplifier which is a Vincent SP-331 (150wpc/300wpc) and I prefer the MC2200. I have also tried several other borrowed amplifiers from friends ranging from Parasound, Conrad Johnson, Prima Luna, and Bryston and with the exception of the Bryston, I still preferred the sound of my old McIntosh amplifiers. The Brystons were the 7B-ST monoblocks and what impressed me the most was the incredible bass I heard from the Aerius which I did not think was possible from their 8" woofers. Some folks have had good luck with class D amplifiers which may be easier to find within your budget, even new. Whatever you decide to get make sure it can handle 4 ohm load with ease. Generally, amplifiers that double their power as the load is halved tend to have good drive for demanding speakers like ML ESL. If you're fixed on getting something new, one option might be the Schiit Vidar with 200wpc at 4 ohms.
Hope this helped.
