I find cartridges are more of a suit to taste component: once you get above the low entry level, one isn't necessarily "better" then another. If you like the Denon DL-103. I say, stick with it - they make fantastic music. Maybe buy another different cart and swap every so often for a different presentation...
But, there are ways to get the most out of DL-103. I would recommend a Cinemag based Step Up Transformer (you can build your own quite easy). I would also recommend an aluminum body cap for the cartridge.
https://www.stereophile.com/content/bobs-devices-cinemag-1131-phono-transformer
http://cinemag.biz/phono/phono.php
https://www.denonaluminumbody.com