So I got a chance to play with my new Crown X1000 amp with my Energy RC-70 speakers this weekend. Sound & Vision tested the RC-70's in March 2006 and rated the sensitivity as 89db. So not really difficult to drive by a decent receiver.
I've got a Denon AVR-989 receiver which is rated at 115W/channel stereo by the mfr. Sound and Vision did a review in 2009 and measured the 989 as 130w x 2, 112 x 5 and 100W x 7 so the receiver is no slouch.
But the Crown X1000 is currently $99 and rated at 300W/channel @ 4 ohms and 200W/channel @ 8 ohms so I wanted to experiment. I did all my testing in 2 channel.
My Denon is sitting on the Crown amp right now and since there are no top vents on the amp there is no danger of it overheating. It has front vents and fans on the back so nothing is blocking any air circulation.
First thing I did was turn off the subwoofer in Direct/Stereo mode and the RC-70's were set as large. Then I broke out my Radio Shack SPL meter and made sure the test tones read the same level using the Denon internal amps and the external Crown amp.
Then I ran everything in Pure Direct on the receiver with my CD changer connected with analog cables. Played several of my CD's which I know very well. Probably listened to music for a good 3-4 hours over the weekend.
At first I thought music through the Crown sounded fuller. But after switching back and forth several times I couldn't really tell a difference between the Crown and Denon amps at my normal listening levels. My listening room is only 16 x 13 so I rarely go past -15 in stereo mode. I cranked it up to -10 and it was too loud for me and the neighbors across the way would have started complaining if I left it on that high much longer. Maybe if I could have pushed it to 0db on the dial the superiority of the Crown amp would have shown. Or if I had 4 ohm speakers like Mangepan or Polk LSi it would have made a difference.
Batpig said a few posts up that if you never turn your receiver up past -20 or -15 you're probably not using much more than 10W. Maybe he's right.
I'm gonna keep this amp and possibly use it for Zone 2 or another purpose. Since the price was so good I see no reason to take it back. The only drawback is the bright blue power light but a little electrical tape will take care of that problem.
So if one has a very large room or difficult to drive speakers I recommend buying an external amp like the Crown X1000. They also have the X2000 for $199, and X4000 for $299 at Guitar Center and Musician's Friend. I just don't need that kind of power.