About 5 years ago, starting with the Summit, MartinLogan introduced their first powered hybrid. A hybrid is a combination of both electrostatic panel and cone woofer. A 'powered' hybrid has a built in Class D SS amp just for the woofers.
Previous (unpowered) hybrid models were a problem for those who wanted to get the best sound out of the electrostatic panel, which requires tube amplification. Unfortunately, tube amps aren't so great at controlling the woofers, unless they are really powerful. So you had three basic choices:
1,) Use a SS amp for great bass and put up with bright mids and highs from the panel. And the SS amp will need to be 200W+ per channel in order to deliver enough current to drive the panel at low impedances. You see, a 100 watt SS amps can't deliver much current, which is what stats need. A 100 watt SS amp CAN deliver lots of voltage (good for cone woofers) but electrostats don't need lots of voltage from the amp.
2.) A 100 - 150 watt tube amp. Terrific for the stat part because it provides plenty of current, but guaranteed to provide dissapointing, sluggish bass (no "thwack!") Remember, the original Quad 57 was driven by a 15 Watt Quad tube amp, and later a 40 Watt. It was a pure electrostat, and didn't have much bass, but nobody complained ;-)
3.) You could bi-amp the hybrid using an external stereo crossover and a tube amp for the panel and a SS amp for the woofer(s). If you know what you're doing and have the scratch, this setup can provide spectacular performance. (read my system history.)
Back to the CLS. I've had my CLS-IIz's since 1992, and they aren't going anywhere. In that time I've powered them with the finest amps both tube and SS: ARC M300 Mk2 (8)-6550 power tubes per side (300W ultralinear mode, or 140W triode mode @ 2,4,8 ohms), the incredible Mark Levinson 23.5 SS dual mono (200W @ 8 ohms) and currently, a McIntosh MC275 (95W @ 4, 8, 16 ohms) Due to Mac's proprietary power circuit design, the McIntosh puts out lots of current and predictably sounds better than any amplifier I used so far.
My point is that if you only have to drive the electrostatic panel, there is nothing to gain (and a lot to lose) driving it with a SS amp - even a very expensive and/or high-powered SS amp! This has been shown to be true over and over again. The problem (until recently, when ML finally came to their senses and provided built-in SS woofer amps in their hybrid speakers) was that there were only three full range electostats in the market: the CLS series, the later model Quads, and the SoundLab series. And to be honest, you needed a SS powered subwoofer with the first two. Now ML produces another pure electrostat, the CLX series, which is $25K+ (like SoundLab) and it too can use a subwoofer from all accounts! HOWEVER, it's revealing to note that when ML introduced the CLX at the Munich Audio Show last fall, it was driven by McIntosh 2301 monoblock tube amps!
So: if you want the most out of your CLS, buy it a nice reliable cool-running McIntosh tube amp. BTW, the CLS only goes down to 40Hz on a good day ;-) If you want bass, buy a ML Depth sub to match, and you'll have one of the finest sounding systems any amount of money can buy.
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