2647 is pretty far aft, so you'll definitely get some noise from the engines and rotors.
I had more than one question about the noise on Deck 2 while I maintained a "Let me answer your questions, 'live' from the Magic" thread (<a href="http://www.disboards.com/showthread.php?threadid=38440">link</a>) during our 5/26 Magic cruise, so I went down to Deck 2 and did my own evaluation.
First of all, let me state that, for the majority of the rooms, Deck 2 is very quiet and you should have no problem staying there. But there are some zones where staterooms are near loud mechanical equipment (electrical lockers, transformer rooms, a/c equipment rooms, ship's propellers, cargo hatches, etc.).
So with the disclaimer that "your mileage may vary" and that you may be willing to put up with the "dull roar" in exchange for a good fare, these are the rooms that are in noisy zones:
<nl><li>2000 - 2004
<li>2032
<li>2036 - 2045
<li>2078 - 2085
<li>2088 - 2096
<li>2114 - 2129
<li>2139 - 2153
<li>2500 - 2520
<li>2534 - 2547
<li>2586 - 2600
<li>2626
<li>2630 - 2653</nl>
Also, on Deck 1, you might want to avoid 1030 - 1037.
The noise in these zones is not so loud that it would ruin your vacation, but if you are sensitive to noise, you would probably want to consider another room or be sure to bring earplugs to wear when you go to bed.
