I've been experimenting with amp isolation for quite a while. I don't know that there is any one answer that fits all needs, although I hear the Grand Prix is the best out there, pricey though.
When listening to various isolation components I first listen for any dampening effect. No one can tell you how much or little dampening you may want, experimentation is necessary. Your choice will also be largely dictated by whether your floor is suspended or on a slab. If it is suspended I would first find a way to mass load the floor where amps will be located, I use massive slabs of concrete (fireplace threshold). I've also heard that jack stands supporting the floor directly underneath stands works well. Equipment racks that are spiked directly into a suspended floor are compromised greatly.
When listening to various isolation components I first listen for any dampening effect. No one can tell you how much or little dampening you may want, experimentation is necessary. Your choice will also be largely dictated by whether your floor is suspended or on a slab. If it is suspended I would first find a way to mass load the floor where amps will be located, I use massive slabs of concrete (fireplace threshold). I've also heard that jack stands supporting the floor directly underneath stands works well. Equipment racks that are spiked directly into a suspended floor are compromised greatly.