Did you try other amps with the dx300? I remember that the amp12 improved the sound even more, giving it more controll, dynamics, clarity, stage and separation. It was less colored but more like a typical class A sound (well the amp12 is a class A amp). I remember not liking the dx320 with stock amp but the amp12 changed everything for me. The stock amp sounded loose, muddy and sharp at the same time. With the amp12, the overall sound matured a lot and it was very very close to the dx320 but bit warmer.