RCA or XLR

Guys, thanks for the informative and enlightening posts. I have switched to RCA but it has helped only marginally.  I will look at those links and pursue.  Thanks again. Mark  

Using the SYS as the preamp is not a bad idea.  I calculated out the gain on the Aurum (75 mv input sensitivity with a max output of 16v) and it is an insane 47 db.  To give you an idea, with a CD source, there is virtually no amplifier that requires actual gain from a preamp (CD output is 2v, most amps put out max output with 1-1.5 volts of input).  Most preamps have a max gain of 0-15db. 

The result of having such high gain is that you have to run your volume knob outside of its accurate range.  Most potentiometers don't track well in their lower ranges, getting better closer to full output.  Sound quality is generally lower that far down on the knob and ideally, your normal listening volume should be in the middle to top of the volume knob for best sound quality out of the poteniometer. 

So the short is, that you really may want to consider going to a passive preamp, or a lower gain preamp (you might look at the Schiit Saga and Freya).  At a minimum, I would install attunators in between your preamp and amp to get the pot in its linear range.  Here is a link for 12db RCA attenuators:

https://www.parts-express.com/harrison-labs-12-db-rca-line-level-audio-attenuator-pair--266-244
 

This Schitt SYS is another option if you want to use the RCA inputs!
https://www.schiit.com/products/sys

They are balanced but using them will only make your gain issue worse.  You can add attenuators inline which will pad the level down and give you better use of your volume knob range and get it where it is more linear.  

https://www.parts-express.com/in-line-xlr-attenuator-pad-20db--240-416