Are you talking about the Sunfire Cinema Grand or the Sunfire Cinema Grand Signature ? Both are 400+ wpc, but the standard model does that at 4 ohms and the Signature does it at 8 ohms.
Either way, the Sunfire's need a "real" low loss 20 amp circuit if you want it to operate like it should. They are efficient amps but due to their high output, they still draw big power. They also work best if you can feed them via their XLR jacks i.e. in balanced mode. Then again, the Pass is probably biased relatively richly, so i would think that it would also need a good dedicated AC line.
The Sunfire runs relatively cool, even if you are getting on it for an extended period of time. In order to "help" keep it cool, it works best if you can elevate it up off of the shelf a bit. Most of the heat that they do radiate comes out of the bottom of the amp. The Pass will probably run noticeably warmer and require more effort in terms of dealing with the radiation of heat.
As far as sonics go, i would think that the Pass would have enough power and sound better. Then again, i do not know how loud you like to listen and / or what the room acoustics are like. If the room is rather "dead" i.e. heavy drapes, fully carpeted, large stuffed furniture, etc... it is going to take more power than if the room was sparcely furnished and much "liver" sounding.
Personally, i like both amps and own multiple products from each designer ( Pass & Carver ). I prefer the sonics of Pass products but the sheer "grunt without straining" that the Sunfire's provide is pretty hard to beat ( if you need that type of performance ). That's why i have Pass products in my 2 channel system and Sunfire in my HT. Sean
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