I have no experience with the 108. The Denons I have heard/owned (MC), all were very good value, rather neutral, with an emphasis on musicality. I would guess that $56 would be a good investment, but not for this. Output is even lower - 2.5mV.
What about the Grado? The 440 should work great on a Dual. If the Grado doesn't hum on the table, John TCG (our moderator) can tell you how to make it sing even better. There should be some old threads about that. It involves a drop of silicon on the coils, a new stylus, and an outrigger.
So, you're running a buffer sans line stage. Great if you can get away with it, but most systems need the 8 to 20dB of line stage gain. I used to use a passive with a 0.2mV cart and 67dB of gain from my phono stage. Still, I had a small listening room and efficient speakers. With that same set-up in the larger room it's in now, no way. Finding a decent line stage is a problem. They all suck, unless you spend a million dollars. If you like tubes, a Herron might be the ticket. I always like Spectral for transistors. I have a new one on the way now. It's a JC-2 clone - uses matched FETs. It doesn't have all the controls like balance, that degrade the sound. I'm trying not to get my hopes up. LOL
neo