Bluesound mode not really cutting it

There is nothing wrong with the Bluesound Node when used with a competent external DAC. It wouldn’t constitute a bottleneck even if your system were anchored with $20K speakers. Its UI is better than most as well.

You would be far better off investing that $3K into better speakers, and to a lesser extent, better amplification. 
 

I am not familiar with the Black Ice DAC, but if it’s one of those that incorporates a tube buffer, then chances are you’d get a considerable improvement by moving to one of the perfect-measuring “Chi-Fi” units from Topping or SMSL. Even if, say, your system was anchored with $12K speakers, the Node and a Topping DAC would not be your bottleneck. It’s far more likely that the room or those $12K speakers would still be your bottleneck. 

+1 CXN100 or its budgetary ed. MXN10

The MXN10 is a joke compared to the Node IME. In addition to the fact the Cambridge doesn’t sound any better, its UI was obviously designed for the tech illiterate. It allows almost zero customization of anything. The owners might as well use the native app of their chosen streaming service.

For a couple hundred more, the Eversolo A6 is a superior unit in every regard. 

@skiznfliz thanks for that info on tube rolling with the Black Ice FX DAC. I would hazard a guess that there is likely a discussion forum somewhere on doing just that. Glad you found some NOS tubes that can bring the magic. Maybe the OP should try that as well before buying a new digital streaming transport. 

@audioman58 Yes, the Node is "good" and at $600 has been considered "the" entry level streamer to get for many years until WiiM came along with their lineup which includes their well-reviewed "Ultra". Currently the Node is on discount for $349 since Bluesound is doing a refresh of their streamer line up. Even at the $349 price, you have to figure they are still making about $150 on it. Mark up of devices is just part of the game when buying consumer items, especially those made in communist China. But hey, everyone wants to save a buck I guess. So many speaker manufacturers have theirs manufactured there it is hard to avoid at most sane price points. 

Sorry to post so many times, but it just occurred to me that since your Black Ice DAC has a volume control, have you VERY CAREFULLY set it properly and hooked it directly to your amp and bypassed the Schiit Saga, just to answer the question of whether or not the Saga might be your weak point? At least you’d know one way or the other. I like Schiit gear and think it is fine, but well, it is worth a try.

TMR has a Bryston BDA-3.14 streaming DAC. The Manic Moose interface is a POS but the Bryston is Roon ready. Load Roon on your home computer and use the BDA as a Roon end point. Bryston DAC sounds smooth, laid back and has plenty of warmth. Exactly the sound signature you seek. 
https://tmraudio.com/components/d-a-converters/bryston-bda-3-14-network-streaming-dac-d-a-converter/

However, you have a bottleneck in your system - your schiit preamp. May be worth ditching your entire low-fi front end (BS, Schiit and Glass) for something like the used Simaudio Moon 390 which is an all in one DAC/Streamer/Preamp here. 
https://tmraudio.com/components/music-servers-streamers/simaudio-moon-neo-390-dac-streamer-d-a-converter/