The 501 is no upgrade. There are a handful of cartridges at that price that offer much more. Ditto the 901. Actually, IMO, the entire Shelter line is overpriced considering the available alternatives from Sumiko, Zyx, and Dynavector.
Upgrade Denon 103 R to Shelter 501 II?
I own a Denon DL 103R on a Spacedeck with Space-arm. I have read much conflicting data on this cartridge. My question to those who have tried this cartridge and also either a Sumiko Blackbird and Shelter 501 II, is: Will either of these be a significant upgrade? (System: EE Mini-max phono-preamp, Jadis DA 88 Signature int amp, Merlin TSM-Mx speakers)