Group delay in subwoofers

I understand the phenomenon of group delay when subwoofers are connected to a preamp and that they need to be placed approximately 8 ft closer to the listener than the mains.  Is this also the case when connecting a sub through the speaker level inputs from an amplifier or is group delay much less of an issue in this configuration?

Thanks for the comments.  I had a feeling that it wasn't quite as simple as I had hoped.

JC: Group delay for subs isn't as important as the proper phase/amplitute matching through the crossover, room acoustics and EQ.

That's where you should focus your time and energy.
Thanks, Erik.  I absolutely agree and would need to buy a processor to do it the right way.
Rythmik Audio subs come with a plate amp that includes a continuously-variable phase control. The control allows time-aligning woofers to speakers without physically moving either. The Rythmik PEQ model plate amps also provide both low level connection (on RCA jacks) and high/speaker level (on binding posts).
For real and detailed information go to and get ready for some serious reading. Super informative and helpful.