Move up in class means that you may have to spend money, unfortunately. NAD gear is in a class which is built to a certain price level. This is not bad; it is a challenge to a designer and sometimes the solution is very elegant indeed, but the limitations are there all the same. If the designer's budget were doubled or tripled, what would be the result? A unit in a different class.
Since upgrading is expensive, it makes sense to take the biggest step you possibly can. If you can look up from your NAD, as far as to a Bryston, SimAudio or YBA integrated, or perhaps a Portal Panache (which I haven't heard but is said to be good value at its price), these would represent a big step up in class.
Look around here and see what is selling for three or four times the price of a C320BEE. If you have a dealer, ask him for a recommendation. Avoid mass-market gear as a general rule. Have fun hunting!