@cub Here's a fairly straightforward guide to determining whether a cartridge will work well with your tonearm.
https://www.vinylengine.com/cartridge_resonance_evaluator.phpYou will just need to enter the effective mass of your tonearm (the Rega RB330 is 11 grams). You'll see a chart pop up. Then, you need to look at the specs of to get the weight and dynamic compliance of the cartridge(s) you are considering.
The Denon 103r weighs 8.5 grams and has a (very low) compliance of 5 (this is listed as "5 x 10-6 cm/dyne". If you look at the chart, you will see that this combination falls well outside of the optimal range.
Hope that helps, and feel free to ask more questions. There are a lot of experienced audiophiles on Audiogon, and many are very generous with their knowledge.
Cheers,
Scott