Do I need a compressor?

[Dags]

".

or, for the price of a compressor, why not buy another NT1a if you're happy with the sound of it and set it further back and record both mics at the same time. the same kinda rules apply to the above suggestion in terms of editing (i.e the closer mic will probably clip in the loud parts whereas the further mic won't)

This technique was used for David Bowie's song 'Heroes'.
Be aware that unless your room is well treated, the mic that is placed further away may also be picking up more of the room reflections and the resultant recording may sound 'spatially' different to the close mic.
This may be a good thing to use for creating sonic differences between verse & chorus parts.

Dags