Your looking in the right direction, integrated amplifier is the best choice in the lower price range if quality music reproduction is your goal. Also don't be fooled by power ratings, that 40 watt NAD will out power receivers rated much higher than that, its also quality of power over quantity of power.
That 40 watt NAD will probably deliver 75 watts into 4 ohms, and 140 into 2 ohms, Not many receivers can drive 2 ohm loads, so ultimately that little NAD will not only have better sound quality (because of better parts) but will be able to drive lower impedance loads, and deliver more current to better drive speakers.
Ultimately the speakers determine the amount of power needed, as well as the size of the room and how loud you want to play it. Tell the dealer what speakers you have, and he can tell you how much power you really need.
Again it always comes back to quality of power over quantity of power
Get the NAD you'll love it.
Kevin
40 years high end audio video specialist