Can the dryness in midrange with NAD be overcome by changing the source? May be using a Marantz cd player?
An audiophile "tweak" for this is to submerge the output capacitors in water. Try it today!!
As a NAD 325 owner I can vouch that the NAD sound is not everything. It has its sound (or colouration) and if you are lucky to spot it early in the audition phase, don't worry about it, just move on to trying another amp that appeals more to your senses. There are plenty of products in the market to choose from.
Cheers