None of the subwoofers he has appears to have a volume bypass. I just downloaded the manual for the Athena 400 and the 4000. Each manual contains instructions for setup that explain from 4-6 different ways of installation (depending on the sub).

Each method ends with the following:

"Adjust the Volume Control (knob #1 diagram #1) to match the output of the system.
This can be done to suit your personal taste, and room size. Start somewhere in the
middle of the dial and adjust as you feel is necessary."

- ASP400 Manual, page 3
(also on the ASP4000 manual, page 3)

The two RCA inputs on his subwoofer are the typical standard (crossover circuit) input and a bypass for a LFE channel. The volume control does not appear to be bypassed.

I would normally be more civil than this.

Bug,
I am glad you like your NAD, but I question your ability to properly operate your equipment. I am guessing that you have not properly integrated your subwoofer to your speakers and the addition of the bass management in the reciever is too much for you to handle.

First, there is no high-pass applied to the NAD speaker outputs, thus, the speakers are running full-range along with your added subwoofer output. The subwoofer output of the NAD is crossed at 100 Hz, attenuated at 3dB per octave above that.

Second, this means that your subwoofer channel is only down about 6 dB at 200, 9dB at 400, etc - well into the midrange. Without properly using the crossover of your sub, you are using it too high and creating an artificially high output in your low midrange.

Thus, what you are hearing as "authoritative bass" is really a hump in your frequency response of about 20dB from improperly integrating your subwoofer. I would like to see a chart of your frequency response from 20-20K. I doubt it is in any way flat - I imagine it looks like a mountain range.

The Outlaw is both high-passed and low-passed at 12dB. That means that the mains are not being forced to reproduce bass less than one octave below your chosen crossover and the amp will perform better. The output on the outlaw is not weak - you just don't know how to use it.

Further, you probably don't have your speakers set up correctly nor do you have the subwoofer in a position that best integrates with them. You may even be sitting in a null or spike in your room's acoustic response.