My old wavelength audio DAC is still usable

Because your Wavelength Dac is a good sounding well designed Dac with a good analog output stage. The Dac in the Node is compromised by its not very good analog output stage and overall noisy environment.

What digepix says is correct you would need an Dac that can decode/unfold  MQA files. No guarantee a Dac that does that would sound better than your Wavelength however.

The MQA files you are listening too aren't just MQA they are also new remasters so they may just sound better. Are you able to observe the sampling rate when you play the MQA's?