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.  

I am a little confused. Where does the signal get split?

Is your preamp feeding ONLY the crossover? Or is it feeding an amp AND the crossover?

Best,

Erik

Erik, note in the initial post that he is connecting the LS17 to the DS450 power amp directly, via XLR.

Treble gets a little less extended.

If the cable length from the LS17 to the crossover is particularly long, and/or if the cable has high capacitance per unit length, that could be a contributing factor in addition to the impedance issue that has been cited. The capacitance of the cable to the sub crossover will affect the signal received by the DS450 essentially the same as if the only cable present on each channel was the one connecting the LS17 to the DS450, and if the capacitance of that cable equaled the total of the capacitances of the two cables you are using. In either case, given that all of the preamp’s output connectors are driven by a single output stage, a low pass filter would be formed by the interaction of the preamp’s output impedance with the total of the cable capacitances that are present. If either cable is particularly long and/or has high capacitance per unit length the high frequency rolloff and/or phase shifts introduced by that filter could occur at frequencies that are low enough to be audible .

Would the preamps up the range not have this phenomenon?

While I don’t have specific knowledge of all of the recent high end models, just about every one of the many spec sheets I have seen for ARC line stages and preamps at www.arcdb.ws indicates a recommended minimum load of 20K. And just about every one of the many schematics I have seen shows the output connectors that are provided for each channel all being driven from a single output stage, with the RCA connector connected directly to XLR pin 2, and with the two XLR connectors (if provided) connected directly together.

Regards,
-- Al

An additional problem is that the RCA is in parallel with the balanced output on the ARC preamp. This means that as soon as the RCA connection is used, the output of the balanced connection is no longer really balanced. There's a lot here that is pointing to the preamp as the bottleneck.