The phrase "significant improvement in sound" is too general.
What sorts of improvements are you looking for?
The next question is, How can you get those improvements most readily? A different DAC is not necessarily the answer.
The most significant changes in sound come from room acoustics, then speakers and speaker/amplification synergy.
It's interesting how many people will simply weigh in on your DAC issue without knowing these other variables. It's like saying "How do I get there?" without letting anyone know where you want to go, or why. It seems people are more interested in saying anything than answering the question you are asking.