active vs passive time delay

[skogs]

Hi. Because of some major room resonance issues, im building a pair of active midbass-assisting speakers. The problem is that the main speakers will be driven directly by the main amp, while the midbass needs to go through a xo.

Will a speaker with a 2.order LP@300hz active xo cause enough time delay to cause problems, while playing along with speakers that is driven directly from the source?

Help would be greatly appreciated!

Btw. Im not talking about phase problems, but the total delay. If its enough delay in milliseconds to muddy up the sound.