Welcome Metro.
I agree with all above. Don't be concerned at all about your receiver unless you plan on playing at extremely loud levels. I'm talking, nobody can hear each other at the party, kind of loud.
I have not heard the M3s or M22 myself but both seem to be very well respected and popular choices. I'm wondering what kind of music you listen to and what your listening preferences are. Many people here strive to recreate the music as close to 'exactly how it was recorded' as possible. Others like to kick up the bass a notch or three.
M22s are known for an amazing accuracy and will do wonders for good source material but I noticed that you said you will be playing all your music from your Iphone.
If that is the case, your music will most likely be stored in a pretty compressed format and the M3s might be a better choice for you. I believe they are a bit more forgiving when playing compressed music. The accuracy of the M22s might tend to bring out the degradationsthat storing music in a compressed format creates.
If you have a PC, there are some great options to avoid this but I want to keep my post simple. Just wanted to mention my thought on the I-Phone possibly coming into the equation.
The M22 owners can perhaps verify or debunk my thoughts on this as I have never tried compressed music via M22s myself.
