Magnepan MG-1 sonically challenged?

Thank you gentlemen, some good interesting and informative points for me a complete Magnepan novice that would like to get into to the world of planars to learn.
I am loaning the MG-1's at the moment in the comfort of my listening room. I am enjoying them very much. Love the mid range, especially drums with 'snare' drum in particular sounding really nice. What freq should my cheap as chips sub SVS PB12NSD be dialed in? The treble is a bit wishy washy though. They are musical and provide enjoyment which is what its all about eh?
Thanks again for your replies.

My sub's frequency range is 40-120hz, I have it set at 50hz, which is a low as the MG-1's go according to a spec sheet I have seen. I am tinkering with settings, lots of time as I have just bought this pair of well kept MG's, the missus is not to enamoured with them, the oak sides are passable (just), but the beige cloth is a no-no, I think some cloth covers are going to be made very promptly. Unless I buy a bigger pair in black!