Well I'm very happy with these speakers and love the sound. I have a 5.2.2 configuration, hoping to soon increase to 7.2.4. I know these speakers are power hungry and I've heard separate amps would drive them more efficiently?
Efficiently.... that term could mean a bunch of different things! - could you provide more context as to what you are seeking?
In terms of "power hungry" - some speakers are difficult loads, and although they will go loud with many differing amps, won't sound their best unless driven with an amp that can provide substantial current and stability (ie: low distortion) into that low impedance... (they won't clip, so there is no obvious nasty... but they may not give their best performance, imaging could be impacted, dialogue intelligibility reduced etc...).
Other speakers aren't necessarily a difficult load, but are simply inefficient ie: limited db SPL's per watt - and therefore require more "simple" watts.... keeping in mind that db spl is an exponential scale, so an additional 3db of loudness (barely perceptible change of loudness) requires doubling of the watts (power) - in perception terms, "doubling" the loudness requires adding 8x the power so the amount of power needed can climb very quickly ... and with highly inefficient speakers can get BIG.
On the other hand, typical inefficient speakers of circa 86db/W will fill a room with sound at the typical average listening level (circa 75db), using between sub 1W (continuous) and peaks of no more than 4W. (!!)... but doubling that loudness level to 85db would require a move from 4W peaks to 32W peaks.
Typical theatre type targets put the peaks at 105db.... and for the same setup described above, that would be peak power needed of 2048W (!!!! - assuming your speakers don't blow up!)
So, substantially more context is needed as to what you mean by "more efficient"...
