Don't think my preamp likes feeding signal to two seperate places.

Looks like  this person ran into the same issue! LOL

https://forum.audiogon.com/discussions/arc-ref-3-main-output-impedance-question?highlight=paradigm%2...

Georgelofi, I am not directly connecting the 555 to the ARC, I'm using a paradigm crossover in line between it.  Apparently it has an input impedance of 20kohms. According to the thread I referenced, this is a not optimal, as well as using single ended and balanced simultaneously from the arcs output. 

thanks for the suggestion, but I don't have quality interconnects to go all single ended.   I might pursue having a buffer made as per the thread I referenced. Seems he was in a very similar situation, with the same crossover unit as I.  

Almarg and atmosphere, you have it correct.  I believe the paradigm crossover unit is 20k, SE, as per my referenced thread. (That user had the exact same crossover, but with a ref 3. It seems I would need to have a balanced crossover, as the ARC doesn't like to have both the SE and the balanced outputs running together. Imho, equipment costing this much should be built with more robust or better implemented output stages. Many of us will utilize two seperate amplifiers or in my case an amplifier and a sub crossover. We shouldn't have to worry about the output stage "choking". The difference in sound quality once the crossover unit is disconnected is amazing.  I had no idea how much I had been missing before.  I will not connect the sub until I can figure out what I will do to remedy this shortcoming, because the bloom and air is too good to give up just to extend the bass. From Preamp to crossover, I'm using a set of 1 meter silver interconnects that were made by a gentleman for me that I no longer have contact with. I do not know it's capacitance. The signal from the crossover is fed mono to the 555se with a  no frills radio shack gold single cable which is two meters.  I would assume the capacitance of the radio shack cable, and the he input impedance of the 555se doesn't matter because the paradigm crossover is acting as a buffer itself, and that the issue is from the paradigm to ARC relationship.  

The paradigm unit is a stand alone crossover, not a powered sub.  The paradigm is fed from via rca from the preamp, which sends a line signal to the 555se, which is used as the amplifier for my passive sub. I do not have speaker input provisions, unfortunately. 

Fundsgon,

with the SMS-1, I just st wedge another set of speaker cables  at  the amp terminals? You sure there are no ill effects from doing that?

Erik, I use two rca's from m the AC to the crossover, and two balanced cables to main power amp.  No splitters used. The signal is split internally in the preamp to all the various outputs. 

So many considerations just to add a subwoofer without comprimising my signal for the main amp!!! Sheesh!

 almarg, thanks for your insights.  Another idea- what if I used balanced to SE converters and used the other currently unused  balanced output on the preamp. Would that put me where I need to be to not have the low pass phenomenon, or would this be a continuing problem. Not keen with the math formulas. I appreciate your help.