1. You do not need another DAC.
2. It is possible that inserting one might improve the sound quality but......................
3. Until you tell us what the rest of the system is and what audio streams you are listening to, it is impossible to say whether adding a "decent" or "half-decent" DAC is going to make an improvement.
Gadgets for the sake of gadgets only make for clutter. There is a tendency on these forums for there to be recommendations based on the poster's personal history that do not necessarily apply generally. Everyone's situation is different.
Kal
