How are you playing your precious MONO Vinyl?

it’s good to know that a standard phono stage with proper mono summing might get you 90% there

I wouldn’t say that is so. The difference using a true mono cartridge is a lot more substantial. Offhand, I would say using mono summing at the phono-stage or preamp with a stereo cartridge gets you more like 70% there, at the most. At least that’s how I would compare the difference in my setup, where I can try it both ways with nearly identical setups for each.

If you’re using a stereo cartridge, I don’t see how a mono phono-stage would matter, versus summing the mono with a switch on a stereo phono-stage (or at the preamp). The real difference for mono playback is in the mono cartridge itself.

I guess it’s something you have to experience before it sinks in. It’s pretty amazing how much better a true mono cartridge can be, especially with well recorded/mastered albums (like some of the Tone Poet reissues).
 

The OP will be using a mono cartridge.  The query is about whether a dedicated mono phono stage would be superior using the mono cartridge to a stereo phono stage using a mono switch  with a mono cartridge.

Bill

This subject has been rehashed many times.  Many of the mono cartridges on the market are nothing but stereo cartridges in which the two channels have been bridged internally. The mono switch on a linestage also achieves mono output into both channels by virtue of bridging the two channels at the output.  So, when comparing this type of mono cartridge to the mono switch, the only difference is that in the one case the two channels were bridged before RIAA correction and amplification; whereas in the other case the mono signal is created after these processes take place. I could imagine reasons why either one is better than the other.  The other factor is that when you use a mono cartridge and compare it to your stereo cartridge, unless you are using the artificially created mono version of the very same stereo cartridge you are otherwise comparing two different cartridges.  Any two cartridges can differ in sonics by virtue of many factors, so it is hard to say in that case that "a mono cartridge is per se better".

@lewm 

The Lyra mono cartridges (Kleos, Etna, Atlas) are true mono cartridges. They are not strapped versions of the stereo cartridges. Dynavector also makes a true mono version of the XV-1s. 

For about $300 one can dip their toes into using a true mono (not strapped) cartridge with the Audio-Technica AT33MONO.

I hope I did not say there are no "true" mono cartridges. I only refer to the type described. Still, the second caveat for comparing is valid; your particular mono cartridge may just be "better" or "worse" than your particular stereo cartridge. Therefore any conclusions are subject to that qualification. I do think even using only a mono switch when playing mono LPs with a stereo cartridge is superior to not using the mono switch.  At least in that comparison I am not using two different cartridges. If you want to get really purist, you can use one of those few mono cartridges that only has two pins and use it to drive only one channel of your stereo system. I've never tried that nor heard it on someone else's system.