New DAC, or new amp?

I've got that upgrade itch. I am trying to smoothe out the sound, and get rid of some grain. I am trying to keep the spending to around $1000. I have an NAD integrated, being fed by Cambridge audio Azur 640C cdp going through a musical fidelity tube buffer. SOnus Faber COncerto speakers, and a rel sub. Cardas Cross cabling throughout. My question is what to upgrade to accomplish this goal and stay withing budget. I was thinking of ading a new DAC (MF Trivista 21). Or, should I really upgrade the integrated. Imaging could stand to be better too. Alright guys and gals.....lets hear those ideas!