Strengths: clean and loud sound, value, good looking and solid components
Weaknesses: the aluminum woofer cones can get dented very easily- be careful
Summary: Originally i ran these without an amp and things sounded good but like everyone says, they like power. during the break-in i wasnt sure if i liked the sound but probably 15-20hrs or so later they smoothed and became muuuuuuch more pleasant. my front door installation has a lot to be desired but the m661's still have a very good full range response. the woofers are alright off-axis but definitely sound better when pointed at you. i'm curious how the bass would change if they were in some kind of enclosure. even in free air they sound great down to about 100 then the bass drops off- still good clean sound -about what you would expect from a free 6" woofer. the tweeter mounts are nice because they can be aimed a few degrees while the mount sits flush. crossovers are big, sturdy, and see-thru. they do a good job and have 3 tweeter gain settings. i had never heard of diamond audio before reading reviews on this site and i decided to take a stab and order them. im glad i did!