Hey Broadstone,
leveraging on Almarg's post:
Here are a couple of links for you to read up on electro-static loudspeakers:
http://en.wikipedia.org/wiki/Electrostatic_loudspeaker
http://www.sanderssoundsystems.com/technical-white-papers/esl-speaker-wp
So, given that an ESL is a big capacitor, not every s.s. or tube amp can drive this large amount of capacitance. In fact, most s.s. amps cannot. S.S amps go into oscillation i.e. they become unstable with a large capacitative load. This can manifest itself as "shrillness" that you were/are hearing. In fact, it is well-known among ESL owners that "special" amps are needed to drive that speaker. Thus, there is good reason that Roger Sanders makes a power amp for his ESL.
If I had to take a wild guess, I bet that your s.s. amp was oscillating while driving the M-L. Oscillation is really bad for the power amp - not only does it create odd-harmonic distortion that destroys listening pleasure but it also literally destroys the s.s. amp over time. Oscillations in a power amp output stage can create high peak currents that can destroy the output transistors (BJT or MOSFET or JFET) over time.
By switching over to a tube amp, as Almarg already indicated, you reduced the amp's ability to source power into a low impedance & you also added increasing output resistance at the amp output - tubes, by their physics, have higher output impedance (which, in technical terms, is like adding an ESR to the capacitor, which adds a stability zero in the overall freq response & could be stabilizing the amp). You stumbled upon a partial solution for reasons unknown to you.
As Almarg already indicated - make sure that your power amp is designed to drive a highly capacitative load. Most amps in the market are not.
Hope that this helps.
leveraging on Almarg's post:
As with most electrostatics, the impedance of your speakers descends as frequency increases, being spec'd at 4 ohms nominally but only 1 ohm at 20 kHz.The reason for this is that electrostatic speakers are essentially one big capacitor! The perforated metal panels in your M-L are what they call "stators" or "grid" & they are stepped up to a rather high voltage (100s of volts) & the see-thru diaphragm is probably the thickness of 2 Saranwrap sheets is called the rotor/diaphragm. The construction of an electrostatic speaker, thus, is essentially that of a capacitor - the 2 metal perforated sheets form the 2 electrodes of a capacitor & the diaphragm is the dielectric material.
Here are a couple of links for you to read up on electro-static loudspeakers:
http://en.wikipedia.org/wiki/Electrostatic_loudspeaker
http://www.sanderssoundsystems.com/technical-white-papers/esl-speaker-wp
So, given that an ESL is a big capacitor, not every s.s. or tube amp can drive this large amount of capacitance. In fact, most s.s. amps cannot. S.S amps go into oscillation i.e. they become unstable with a large capacitative load. This can manifest itself as "shrillness" that you were/are hearing. In fact, it is well-known among ESL owners that "special" amps are needed to drive that speaker. Thus, there is good reason that Roger Sanders makes a power amp for his ESL.
If I had to take a wild guess, I bet that your s.s. amp was oscillating while driving the M-L. Oscillation is really bad for the power amp - not only does it create odd-harmonic distortion that destroys listening pleasure but it also literally destroys the s.s. amp over time. Oscillations in a power amp output stage can create high peak currents that can destroy the output transistors (BJT or MOSFET or JFET) over time.
By switching over to a tube amp, as Almarg already indicated, you reduced the amp's ability to source power into a low impedance & you also added increasing output resistance at the amp output - tubes, by their physics, have higher output impedance (which, in technical terms, is like adding an ESR to the capacitor, which adds a stability zero in the overall freq response & could be stabilizing the amp). You stumbled upon a partial solution for reasons unknown to you.
As Almarg already indicated - make sure that your power amp is designed to drive a highly capacitative load. Most amps in the market are not.
Hope that this helps.