Peter, The way I see it, you would have to use two Y-adapters back to back, as you suggest, to use a stereo preamp to play a mono LP in mono with a stereo cartridge. Such a set-up would put you in about the same place as a "mono" switch on your preamplifier, except you would have the signal-robbing effects of all those connectors in the unamplified phono signal path. That set-up is akin to using a mono cartridge that in reality is a stereo cartridge with the two channels combined to give mono output. This option was discussed at the top of this thread, but I have never encountered any one who tried it. As for me, I learned a lot from Syntax's two long posts. It is his opinion that a true mono cartridge is superior to either of the options I mention here. I cannot argue that, because I have no mono cartridge, but I intend to buy one. I may even buy a Lyra Delos Mono, since Syntax praised it highly. For me, I can only say that flipping the mono switch on my preamp, when playing a mono LP with a stereo cartridge is a very big improvement over listening in stereo to the same LP.