NAD vs. MF Amp - best match best choice?

I've narrowed down my choices to match with my PSB tower speakers (X2Ts) between an NAD 375 BEE (same company as PSB) or a Musical Fidelity M3i or possibly used M6i. So basically my price range is $1700 for the M6i used or maybe half that cost for a used NAD 375 or M3i.

Need help choosing!! i could always put more towards an upgraded DAC with the money saved but if the M6i is a large upgrade, then I"ll go with that amp. Looking for large soundstage, good bass control.

Thanks for your advice!