Upgrade My Turntable - How Much Do I Need to Spend?

Another win for DD turntables! 

Goody, I appreciate the sarcasm but please show me where I was incorrect. Then I’ll apologize. 

Here is a statement I found on another website that is relevant to the mono discussion: "A true mono cartridge has only one coil and is designed to respond to lateral signals only. It does not respond to vertical signals. A stereo cartridge strapped or otherwise manipulated to become a mono cartridge still responds to vertical signals. The introduction of the vertical signal causes distortion and phase anomolies that are not fully canceled by summing the 2 signals. The anomolies are audible. That is why many consider a true mono cartridge (one coil only) to be superior to a stereo cartridge adapted to mono."

So this statement conforms to my own claim that the response in the vertical plane is cancelled.  However, it also mentions that cancellation is imperfect in that it causes "distortion" (without saying what sort of distortion) and phase cancellation (of course it does, that is how the vertical response is cancelled).  But these considerations do support the notion that using a separate "true mono" cartridge may be additionally beneficial, which in part supports Elliot's experience.  But surely the noise resulting from vertical deflection of the cantilever on a mono LP is not doubled.

Goodlistening, I guess you can listen, but I would appreciate it if you would re-read the last several posts about using a mono switch. It was Elliot (not I) who claimed that noise due to vertical deflection of the cantilever (not "volume", the term you used in critique) was doubled if you use the mono mode switch on a preamp to play mono LPs with a stereo cartridge. And I disagree based both on physics (see my post above, please) and my direct experience. Mijostyn may be technically correct but his statement lacking detail and is irrelevant to the issue, which is what happens when you use the mono mode switch to play mono LPs with a stereo cartridge. I have done this hundreds of times, and high frequency noise is always reduced compared to levels that occur when you play a mono LP with a stereo cartridge and use no correction.

The answer is that when you sum the two channels in phase you cancel signals due to vertical deflection of the cantilever. So Elliot was in error to claim such noise is doubled.

Elliot, You wrote, "Playing a Stereo Cartridge even if your Preamp has a Mono Mode: the cartridge will pick up any vertical movement: scuffs, surface dust, dirt in the grooves, very slight warps: then the preamp’s Mono Mode will DOUBLE the unwanted noise in both speakers." 
This is not the first time you have made that claim.  Can you provide some supporting reference?  What happens in a typical phonopreamp in mono mode is much like what happens in most modern mono cartridges, which are bridged internally to produce a mono signal.  So too are phonoline preamps when in mono mode; R and L channels are bridged.  This does not "double" noise produced by vertical motion of the stylus/cantilever, so far as I know.  I'm willing to learn if you provide a reference.  It also goes against all my direct experience using mono mode in the preamp; the treble is noticeably cleaner compared to playing a mono LP in stereo mode.  That in fact is the major benefit as I perceive it.