James, you’re putting waaay to much stock in the numbers you cite, particularly the M1’s frequency response of 20Hz to 20kHz. In the bad old days (pre high-end), mass-market companies at least provided margins for those numbers---i.e. plus or minus 3dB. In other words, the M1 would reproduce a 20Hz signal sent to it, but 3dB lower in level than it reproduces a 1kHz signal of the same strength. The numbers you cite mean absolutely nothing without the "qualifying" numbers that need to accompany them. The M1 20Hz figure may be achieved (though I doubt it is) only with 50% harmonic distortion and 20Hz being 20-30dB down from 1kHz. It’s a numbers game that some companies are still guilty of using on the naïve. Though you now think the 20Hz spec for the M1 indicates it plays lower than the B & W, the inverse may actually be the case. It all depends on how those numbers were arrived at. The B & W 35Hz figure may include a frequency response spec of plus or minus 3dB and a distortion spec of 10%, while the M1 figure of 20Hz is achievable only at 20Hz down from 1kHz and with 50% distortion.
Your amp has the same specs as does your CD player? ALL amps and ALL CD players do! Your M1’s are rated at 250 watts? What do you think that means? That the speakers require a 250w/ch amp, or that they shouldn’t be used with an amp producing more power than 250w/ch? It means neither of those things. You say you think you may be pushing your amp too hard because it is rated at 220w while your speakers are rated at 250w. That reveals you are operating with some deep misconceptions about specs. It’s too long a story to go into here, but with some research you will learn why the real amp/speaker pairing considerations are of a very different nature.
If the above sounds overly harsh or critical, don’t take it personally---all audiophiles go through the same learning curve. I remember being very impressed in 1971 with the specs of my new McIntosh 2100 amp---0.25% total harmonic distortion from 20Hz-20kHz at 105w/ch. Even with these much more complete specs than those you are citing, I didn’t learn for another year (thanks to discovering J. Gordon Holt and his Stereophile Magazine in ’72) that those numbers have very little to do with how the amp actually sounds. It is, unfortunately, much more complicated than that.