Please be gentle with me! 🙏

Your son is probably bypassing the internal DAC in the Bluesound , but perhaps not and he may be using the DAC in the Bluesound.  We know for sure he isn’t using the phone DAC, right?

  As to whether the Bluesound is a better digital transport than the phone, see my earlier answer.  The phone may actually be a good transport.  It depends.  Can’t make the answer more basic than that.

  Now, if you upgrade from the Node into better streamers, I am going to feel fairly certain that the phone will come in second place.  The Bluesound is an entry level product, and a well built phone might match it as a transport, but I haven’t seen a phone that will compete with a higher level streamer than the Node

You have flexibility to try either of the dacs. And you can add an external dac down the road. 

Couple things to toy with:

The LEAK has a ES9038Q2M DAC chip and from the reviews they payed close attention to the implementation. I would bet they they are upsampling the source stream. What is his service? Looks like the LEAK also has blue tooth support. Have him switch over to that and compare SQ. Theoretically that should be a step down. But if he can’t discern the blue tooth he may not be able notice the uptick with the  Node either. If he does not have a HiRez service such as Qobuz give that a trial and see if you get a benefit. This all to get a baseline if the system can resolve minor adjustments and its free.

Sounds better and frees up the phone for all other tasks.

The phone becomes a full function remote instead of a crappy source. Even mp3s (which is the best that most phones can play) sound better on a (dedicated) music device.

Streaming ain’t real streaming until you use a streamer. Before that it’s just a wired in computer. Keep it away.

It should sound better yes a streamer streams a phone does a thousand other things that all create digital noise.