Fran: WPPAPI yerself dude :-) Been a while, nice to see you again! But as I said, with most of my mono CD's I hear virtually no difference engaging the mono switch (I imagine I'd hear more of one if I used a tube preamp and/or player).
Inpep: Yes, agree about the phase aspect as well. But, doesn't *somebody* claim mono playback of mono LP's is superior to stereo playback of mono LP's, despite the same principles applying? If not, who's buying mono versions of stereo cartridges, marketed/sold at an additional $$ premium to boot? (Another characteristic of these devices that makes me question their legitimacy until somebody informs me differently -- in this case, specifically as to why an otherwise-identical product, only needing fewer connections and connectors, and perhaps a simpler stylus profile or a slightly adjusted suspension [if that much], should fetch a few-hundred dollar upcharge over the more complex stereo version. But then again, the prices of high-end cartridges in general bear very little relation to the reality of what goes into their design and manufacture to begin with.)
Eldee: Every once in a while, with certain early-to-mid 60's pop disks, I'll actually *like* the peculiarly distorted sound of the fake stereo versions, probably because in many instances that's the sound I grew up with...But I normally try to own a mono version as well, and the majority of the time with material of this vintage I'll prefer the mono to the true stereo version, with its even fakier-sounding hard left/right "dual-mono" panning.