Physically connect a Bluesond Node 2i to a downline, stand alone Chord Qutest DAC

When you run a digital cable it bypasses the original units DAC.

Yes, the digital out from the Node bypasses the internal dac.  Therefore a straight comparison between dac of the Node versus the dac of the Chord is possible.  All you need to do is switch inputs on your preamp.  You will also need to adjust the volume control since the sound level between the two will likely not be the same.  In my case, volume compensation was necessary.

I have a Bluesound Node 2i feeding a Chord Qutest by both Tributaries Coax and by Audioquest Vodka Toslink.   Both sound very good, but if pressed I’d choose the Vodka Toslink.  YMMV depending upon the actual cable employed.   BTW, one of the nice things about using an outboard DAC with the Bluesound Node, is that for MQA the Bluesound does the first unfold, getting you all the way to 96K.   IMHO MQA via the Bluesound / Chord combo sounds superior to my ears than MQA full unfold via the Bluesound’s analog outputs, even though the Chord is not an MQA DAC.

I also have the same setup with Node2i digital to Qutest which then connects via RCA analog cable to my Parasound P5 preamp.

I found the Qutest outperforming Node2i's own DAC by a wide margin.

I have a Node 2i and Qutest and they are hooked up as follows:
Node 2i RCA analog out into channel 1 of amp. Node 2i coax/optical digital out into Qutest then RCA analog from Qutest into channel 2 of amp. So I can A/B test.
I'm baffled. They both sound EXACTLY the same.
Not even the subtlest difference. Switching between channels 1 and 2 on the amp sounds like not switching at all.
The amp is a Roksan Caspian M2 integrated so should reveal differences if there are any. But they sound IDENTICAL.
I have A/B tested the Qutest with other DACs and can clearly hear how the Qutest outshines them. But through the Node 2i ... no difference between the Node's own DAC and the Qutest. 
Optical vs coax makes no difference either to my ears.
I have had friends listen and agree there is no difference. 
Any ideas?