I have a 2 channel stereo only receiver.

Yes

Their general stated sensitivity rating is 90db. Which is on par with the Axioms. I know some 3rd party measurements of the earlier M3 was stated at 86db but haven't seen anything from the V3 model but it is stated at 92db and 96db (in room). Of course, in room, these ratings will change. It is possible that your Cambridge model speaker is more sensitive. Not really a big deal either way IMO.

I know that of all the recent speakers I've had over the last several years I have to turn the volume up higher on the M3's than any of my previous speakers. Not a lot higher but higher enough to notice.

I've driven M3s with a 5 watt per channel SET tube amp, and with a T-Amp which doesn't put out much more than 5 wpc. The M3s are sufficiently sensitive to play at normal listening levels, and capable of playing at high volume with these low powered amps.

The problem is not the M3s sensitivity. Your Onkyo should be able to drive your M3s at higher volumes than you'd ever want.

BTW, the combination of a pair of M3s and a nice tube amp is just wonderful.

Something is wrong with your M3s or your set up.

It doesn't seem like he is having problems powering the M3's to the listening levels from what I understand. Just more surprised that they need a little bit more dial on the amp than his other speakers?

So what is the issue then? If he said the Cambridge blows the M3's away on sound then there is definately something wrong with the setup..

He simply likes them better? I am sure there is a lot of emotion he is experiencing. It is very common with new purchases, especially when there is some level of disappointment involved.

I give up for tonight. I've been fooling around with the M3's since 6pm. I also have an older pair of Sony floorstanding speakers that I just got out of storage.I did a quick A/B with the M3's and I'm hard pressed to hear much of a difference between these two. I think I need some sleep before I do any more A/B testing.

Are you absolutely certain you have everything wired cleanly and in phase? How do you have the speakers connected?