Nad M25 and what preamp

Hi All,
I have a nad M25 on its way, but just can not dial in on a pre amp processor.
I am not really interested in the M15 because it seems to lack alot of luster for the price. I did see that there was a Marantz AV7701, but thought that it might not be the best option.

Can you all recommend some pre amp processors that would fit well with this amp.

What luster is it that you think the M15 is lacking?
I wanted and don't fall over, but I wanted the ability to connect the iphone via bluetooth or air play. But I went ahead and purchased the M15 HD2.

My M25 will deliver today but not sure when the M15 will get here. Now I need to start looking at cables.