Please be gentle with me! 🙏

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.

  Lots a accolades for the BS unit.  But I agree with @mahler123 the improvement potential is a crapshoot.

Some good older used DAC around on usaudiomart and tmr for little  < $400 for a next phase.

Wadia 121,Benchmark Dac1,TEAC 501, Moon D-DAC

@alan60 All I will say now is thank god your son is into audio! We need more young people, assuming your son is young of course.

Synonnymous?: "Thank god your son has developed an addiction at an early age"