The focus of the change on the diamonds seems to be related to my problem are (extending the response of the tweeters), so it might not be an apples-to-apples comparison there.
The Speakers are 91db efficient. They *should* work off the AVR. Still, I guess there's a little left on the credit card and BB has a Yammy P5000s for either $400 or $500 (or perhaps the Emotiva UPA-5? That's only 125WPC though)
Sorry Jerry, but you just fell headlong into a common trap!
Those speakers are 91 db 2.83 volts 1 meter and NOT 91 db 1 watt 1 meter.
Here is the route cause of your problem and misunderstanding.
Your speakers are rated at 8 ohm but are nothing of the sort. They have a minimum impedance of three ohms. So the way they are specked they are not letting on how much amp power is actually drawn from the amp to maintain that 2.82 volts. A sensitivity rating does not correlate with efficiency! When rated like your speakers it tells you nothing at all by itself, about how much amp power you need.
I can assure you the large B & W 800 series speakers like most esoteric three ways, take just gobs of power below 600 Hz. The phase angles are also highly adverse, and three ohms is not even the whole story, as at some frequencies the power drawn is equivalent to a load actually below 2 ohms.
So your receiver will be highly stressed trying to drive those speakers, and actually likely only able to deliver about 25% of its rated power before clipping.
Now I will tell you a story that illustrates how power hungry these beasts are.
When my friend had those 800Ds installed by the dealer, the dealer used the 8 ohm taps on the auto transformers in the Mac amp.
When I first came down to give them a listen, I realized something was terribly wrong. The highs were harsh with the speaker pushed, and the bass was just not filling out.
So I immediately suspected what had happened, and found the transformers on the 8 ohm setting. I told Phil that these might say they are 8 ohm, but they are anything but.
So I changed to the four ohm tap, and it was like night and day.
Phil was curious and phoned the folks at Mac. They have 800Ds there. They confirmed that I was correct that they should be set to the four ohm auto transformer tap. Further they said that the 800 series were among the most difficult to drive speakers they knew of. They told him, that his amp was about the smallest of their amps they would recommend to drive his speakers properly.
The problem is that you are now playing with a highly sophisticated esoteric speaker, and everything else has to be of the same standard, or you will not benefit from owning those speakers.
The difference between the types of systems we are talking about and very highly engineered esoteric ones is huge. It's a chasm.
I recently snagged two nice used Quad 909s. I got both for about half the cost of a new one. The second one arrived yesterday.
I have just been installing them so that I now have 909s powering all the drivers in the front three speakers. So that is 1500 watts on the mains and 500 watts on the center. So the total bill for the front three is 2 KW now. 2.6 KW for the whole system. This is comparable to the kind of power Bryston are providing for their large TL monitors.
It really does take that kind of power for esoteric speakers. I just got though playing Glinka's Russlan and Ludmiller overture, which and concert opener to end all concert openers, and to all intense and purposes I was right in front of the orchestra and everything as it should be.
So to sum it up, if you keep those speakers you will have to learn to piss in the tall grass.
