The Delos is a very significant upgrade from the Denon, but you will have to raise the arm significantly to accommodate the extra height. As I recall, you may need 3-4 Rega shims. I personally had no problem with that, but some people don't like to change the Rega arm height for some reason. I'm not 100% sure, but I think the Goldring Eroica MC may well work in the Rega without shims or less anyway. It's a very nice cartridge for under $1K, IMO.
