My pre amp has 2 sets of line outs so power amp will be supplied also. But the sub has only lfe in (left & right) i am not sure if it has an internal cross over?
No high lvl input. Should i consider another sub?
Your subwoofer does have a crossover, that is what the "low pass" knob is. Low pass, as in, the low frequencies are allowed to pass, the high frequencies are blocked, at the frequency specified via the knob.
You have to be very clear about what you are talking about when you say that your preamp has two sets of "line outs". Usually, the pre-amp outputs are labeled as "pre-out". Those are controlled via the volume knob. A regular "line out" is usually NOT controlled by the volume control, and is meant to send a full-volume signal to the input of a tape deck or similar for recording purposes. You would only want to use a pre-out, so that your subwoofer is controlled via the pre-amp volume control just the same as your speakers. But different brands sometimes use slightly different naming conventions.
Assuming that you only have one set of pre-outs, then use one Y-splitter on the left channel and one Y-splitter on the right channel, run one pair to the speaker amp, one pair to the subwoofer. Your subwoofer has stereo inputs (right and left) so just plug both channels into the subwoofer. If you do have 2 sets of pre-outs, you can omit the Y-splitters, but again, make sure they are actually pre-outs and not regular line outs.
Try the phase switch both ways and use whichever sounds better. The purpose of the phase switch is to make sure the bass from your subwoofer compliments the bass from your mains, rather than cancelling it out.
