PS1 Power Stand / Bass Line Out
PS1 Power Stand (Classic) / Model I Bass Line Out and B1 behavior
Hilmar-at-Bose. This is based on the design goal that “You should always sound the same; no matter how much Bass stuff is attached” I can try to explain my view of why this is a good design goal (of which you may disagree) but let’s look at the actual behavior first.
Without Bass Line out
- 1xB1: 40Hz-180Hz, B1 specific EQ, some nominal gain that we call 0dB
- 2xB1: 40Hz-180Hz, B1 specific EQ, -6dB as compared to nominal
With Bass Line Out
- 0xB1 connected to Power Stand: 40Hz-180 Hz, flat, roughly the same gain as 2 B1
- 1xB1 connected to Power Stand: 40Hz-180Hz, B1 specific EQ, -6dB as compared to nominal
- 2xB1 connected to Power Stand: 40Hz-180Hz, B1 specific EQ, -12dB as compared to nominal
What this complex behavior does is the following. No matter if you attach 1, 2, or 4 B1s, you will get pretty much the same balance between all combined B1s and the L1s. It’s a little off for 3, 5, 6, 7 & 8 B1s, but still reasonably close.
It’s true that the user doesn’t have to re-EQ our systems if you add more B1s or even a PackLite with another pair of B1s. But that’s unique to our system, because we were actively measuring the number of B1s attached. So re-EQ is required, but the system is doing it by itself without any user involvement required. 
With More Than 4 B1s
A little more insight.  We actually can't measure the exact number of Packlites, so there is a slight error if you use anything but 1,2, or 4 B1s. For 6 B1s you will be 3.5 dB bass heavy, for 8 B1s it'll be 6 dB. However, these are rare cases, and if you go through the trouble to hook up 8 B1s, I guess you are actually looking for something more bass heavy.
Don't ask how I know.