I purchased the option for variable outputs for $100.  There are outputs, but no volume pots associated with these outputs.

The manual doesn't mention them either:

"RCA OUTPUT JACKS
You can have your amplifier configured with line level outputs that can be used to drive a second amplifier or subwoofer. These RCA output jacks are located directly next to the speaker binding posts. You will find that these are healthy outputs that will make whatever is plugged into them sound more like the amplifier itself. This is possible by
taking the output jacks directly from the amplifiers output transformers. That makes the signal coming out of the jacks rich with even order harmonics that can make even a solid state amp plugged into them sound more like tubes. This of of critical importance

if you plan to use them in a bi-amp system or to drive a subwoofer amplifier(s) because either one will sound and therefor blend much better with the SE34I.4’s sonic signature. In fact, if you change tubes in your amp and consequently change the sound, the
sound from your second amplifier or subwoofer amplifier will also change to match, automatically!"

I guess I just did not ask enough questions and should have not assumed there was a volume control for the variable output.  I'm assuming what makes them "variable" is that they are controlled by the same volume controls as the amp itself.  Is this correct?

Assuming this is correct, does anyone have any ideas for a simple and small volume control that I can use between the Rachel and my other power amp I'm wanting to use to power the bass bins?  I fully believe that my bass will need to be limited to match the Rachel's output to the mid/highs, although I have not run any tests to confirm.

Thanks, I didn't realize something like those RCA level attenuators existed!  Worth a try at that price

I think I’ve decided on this with a volume control.  It’s passive too.

https://www.schiit.com/products/sys

I received my passive Schitt today.  Works as expected.  I was able to bi-amp and send the Decware signal to the mid/high of the left klipschorn.  And the adcom 555II to the bass bin.  I hooked the entire right channel off the adcom entirely for initial testing.  Both signals, R & L went through the Decware then schitt.

So my findings are that biamping will now indeed give me way more power than I need.  The adcom gives way more punch to the bass bin, as expected. The Decware is a lot less harsh/schrill in the upper frequencies than the adcom.

I need to biamp the right channel next. This requires a bit of effort to get to and move the klipschorn so I can do the wiring.  But the proof of concept testing is good.

Before I biamped, but after going through both the Decware and schitt, I experienced a few issues that I didn’t notice after.  I will need to test again once the biamping is complete.  But I got some crosstalk between channels. When I had Decware right volume down to zero,  could hear sound in the right speaker. And when I passed the signal direct from Decware to the adcom (no schitt), I got some very significant 60hz hum.  But both issues seemed to go away after making my test connections as described.