Parasound P6 DAC vs Denafrips Aries ii

I just purchased a Parasound P6 Preamp.  I have been comparing the P6 DAC with my Denafrips Aries ii DAC.  I can't tell the difference.  I have been using my Cambridge CD transport and switching back and forth between outputs with the same CD playing.  Am I missing something?  I am asking because I am considering switching out the Aries ii DAC to another system in another room.  My system is amp Parasound Halo A21+ , KEF LS50 speakers, 2 REL T/7i subs.
Dac differences tend to be small relative to other changes and can be harder to distinguish in quick listening. Either give it more time to see if differences emerge or be happy with the sound of your P6 and move the Aries elsewhere.
Thanks!  Do you have any suggests how to compare DAC's?  DSD files, Classical symphonies, streaming HD music?
I re-programmed the Denafrips Aries ii to oversampling and slow filter.  I would say it now has the edge over the P6.  
Hello @aeschwartz,

Some tricks for Ares II:

1. Keep it on 24/7 for best sound

2. Use only the RCA or XLR output, but not both at the same time - the output are shared, connecting both output may degrade the SQ depending on the input stage design of the connected devices. 

3. Configuration Guide for NOS/OS:

Alvin Chee
The phase setting changes/invert the output phase, i.e. 0° or 180°. 

It depends on your audio chain. You may try the phase inversion to hear the difference, and stick to one that sound the best.

Hope this helps!

Alvin Chee