"Leonid Makarovsky" wrote ...
By the way, so for sub-woofer going from receiver to a
sub-woofer with built-in amp do I need 75 Ohms or not?
Also my soundcard shares mini-jack female output of LFE
with center channel. Will I need 75 Ohms for that too?

If it is digital, yes, 75-ohm would be best.
If it is analog, no you do not need 75-ohm.
Simple as that.