"Double" bi-amping a good idea?

As a slight correction to earlier comments, Tekunda's current configuration is not really what is considered bi-amping, rather, it is bridging or monoblocking since one amp drives each speaker full range. This further complicates the impedance issues by effectively halving the already low impedance presented to the amplifier...
That's why my suggestion of putting the amps back to stereo mode and vertical bi-amping makes a whole lot of sense in this case.

If you really want to improve your sound sell the Bel Cantos and buy an InnerSound ESL amp. The ESL amp was specifically designed to drive the complex loads that electrostatic hybrids present, and a single stereo ESL amp will give you just as much power (if not more) than the 4 bridged Bel Cantos you are considering. If you did a vertical bi-amp with two ESL amps you'd have more power/volume than your ears could possibly stand and better sound to boot.

Tekunda, another thing to try before you buy anything else would be to use the Bel Canto amps in their stereo mode to drive the ESL panel and bass section of each speaker separately. This is the configuration for vertical bi-amping -- right now, with the amps in mono you are horizontal bi-amping. My guess is that vertical biamping would result in better quality sound -- not louder -- but better. Try that and let us know what you think. If that still doesn't float your boat then you may want to consider my previous suggestion of going to the InnerSound amps. I doubt that using two pairs of the Bel Canto amps will give you what you are looking for.

Tekunda,

I never said that you needed an external active crossover to bi-amp. You can just use the passive crossovers in your speakers. Going to the vertical bi-amp configuration should improve your sound noticeably without you having to buy anything else.

Later, down the road if you feel you want to go to an active external crossover you can always do that and it will likely improve the sound even more. You can get a decent active crossover used for under $500. The hardest thing will probably be taking your speakers apart to disconnect the passive internal crossovers (lethal voltages may need to be discharged too) but the folks at Martin Logan would be able to advise you of just what is involved to accomplish that. They could also advise you as to what crossover frequency and slopes to use. It could be a fairly simple, straight-forward operation, so it wouldn't hurt to give them a call just so you'd have a complete view of all your options (before you rush out and buy the crossover and then find out that it's not a job you'd care to tackle). Happy listening!

Sean,

You have done a very credible job of explaining the complex loads that electrostatic hybrids represent, and I thank you for your effort and all the good information.

One additional point I'd like to bring up is that while tube amps generally excel as voltage amplifiers (which is why many use them to drive ESL panels) they do not deal with low impedances as well as solid state designs. So in the typical ESL panel, where you have that low impedance dip at high frequencies, the power that most tube amps can deliver falls off rapidly. However, in such designs, sometimes a bit of high-frequency roll off is perceived as a good thing by listeners.

This was one of the biggest problems I had in finding a suitable amp to drive my InnerSound Eros, which dip to 2 ohms in the high frequencies. The tube amps I tried, although they sounded nice in the midrange, noticeably rolled the high frequencies. Even the highly-respected Clayton Audio M70's, a solid-state, high-current design that exhibited wonderful high frequency reproduction with many other speakers, failed to maintain its level of treble performance on the Eros. With such a load it cannot be taken for granted that every high-current, solid-state amp will be up to the task, and many that I tried were not.

The InnerSound amp, which is stable to under 1 ohm and delivers 1200 Wpc into 2 ohm loads sounds utterly unrestrained, detailed, and airy. At the same time, it is also quite adept at providing plenty of punch, extension, and control in the bass. Of all the amps that I've tried with the Eros so far, the InnerSound Amp and the Monarchy Audio SE-160 hybrid monoblocks have provided the best performance.