Is AIR getting better in the Pro era? Thoughts of little steps.....

[ogs]

Anyway, bypassing the switch and feeding Roon directly (Ethernet) into Air seemed to work OK on basic settings, although I felt the sound was better resolved through the mRendu. When dsp was switched on in Roon, I suffered regular 'scratching' and drop outs. I could only use the direct connection satisfactorily with dsp disabled. In contrast, running through the mRendu, it is totally stable including with dsp switched on and the splitter switch in circuit.

Very strange that you'd get unstable sound with AIR and DSP and not mRendu and DSP. The load on Roon Core is very similar for both, might even be a bit less with AIR than RAAT.
Are you sure you used the same DSP settings for both? I run Roon Core on an i5 NUC (Debian Linux) and can stream to a mR or AIR direct without any problems. I use the DSP in Roon for both PEQ and convolution. Have you tried to increase the buffer setting in AIR? (the default setting=500ms for wired).
Maybe this post by Brian Luczkiewicz over at the Roon forum can help clarify: https://community.roonlabs.com/t/crackle...et/28559/4