REL subwofer High Level vs Low Level connection

Ryriken, I suspect that you mean that he says to use the main speakers full range, as opposed to high pass filtering their inputs (i.e., filtering out the deep bass content of the signals that are provided to them). That's a different question than what is being discussed here. Among other factors, the answer would depend on how well the main speakers can deal with deep bass frequencies. I have no doubt that his recommendation is correct for his speakers.

Elunkenheimer, you're welcome! Columbia EE here :-)

Best regards,
-- Al

I run my sub High Level.

Good for both ee types here . My question to add would be. Does an air gap opt affect group delay as E lags for inductor? lbsu me so idk.

Lewhite, not sure that I understand the question, but the group delay behavior of an inductor will depend on both the amount of inductance and the design of the circuit that it is part of. Whether the inductor has an air core or a ferromagnetic core is not in itself relevant to that, although the two types may deviate from the behavior of an ideal inductor in ways that differ.

Also, current (I) lags voltage (E) for an inductor, not vice versa.

Regards,
-- Al

Al that reminds me of Eli the Ice man