Shelter 501 MkII vs Soundsmith Carmen mkII
The Carmen mkII's output is 2.1 mV against the Shelter 501 MkII's 0.4 mV, its tracking force 1.4 g against 1.6 g, and its channel separation 26 dB against 25 dB. Both share cartridge type (MM).
Both turn up in the same documented systems.