Innersound Kilowatt Monoblock, how good is it?

The InnerSound amp will drive 1-ohm loads at high power with no problem. The Pass will run a lot hotter and won't be nearly as comfortable with the 1-ohm (better consult Pass). Plus, I believe it will only deliver about half the power of the InnerSound, if that...

I assume these are the later Stradivari Cello's? Adding to the above, are you sure you can drive them full-range with one amp -- however powerful that amp is? Another point is that *I* happen to like Inner's sound (sorry, how else can I phrase it:), but more importantly so must YOU. Don't buy the amp for its 1-ohm driving abilities -- you can factory mod. other amps to do this too...and there are other amps factory -set with that capability
(Symphonic Line's Kraft classA series is also set to drive below 1-ohm, fro example; I've used it in such "applications".)
BTW, for the Pass I would CERTAINLY consult the manufacturer before connecting the amp to the speaker, as Plato suggests. Nice speakers!

Thank you all for the kind answers.
I have used the innersound ESL amp with 300wpc at 8 ohm in vertical biamp configuration(each channel driving half of one speaker) and like the result. Since I have only one amp I can listen to only one side of the speakers but the sound is very promising. I will wait to get another unit of ESL for another channel. The amp, hower, runs quite warm which is indicating that it is working hard with the load despite the biamp config. From my calculation, the ESL is capable of providing 1200 watts(2 channel)for one channel of my speakers while the Kilowatt can provide 3200 watts for one channel(at 2 ohms).
I agreed that the X600 may be sweating a bit at 1.5 ohm load so I probably have to use 2 units of X350 in vertical biamp config.
I have discussed with Roger Sanders from Innersound on email and he is very helpful in providing the info. I hope my request to purchase the Kilowat amp can be finalised or I have to consider other option.

The amp running warm could also indicate the biasing, I think. My DNA 1.0 idled much warmer than the 0.5 ran, and S. McCormack indicated to me that that was normal.

you might want to check the review of the Innersound ESL 800 monoblock amplifier at www.UltraAudio.com
The 800 is between the 300 and the reference and is a very good value, better now than it will be when the price goes up on Nov.1 -- but an excellent choice, especially for your needs