The lambskin perf Auteur pads will be slightly darker in highs compared to the Auteur hybrid and Universe lambskin pads.I know it’s the recording but some songs the Atriums sound a bit sibilant or harsh. Not sure in which frequency range. Maybe 5k? Or lower? I’m hoping the solid mesh will tame it. It only happens for certain sibilant tracks.
The Atriums make me want to add a tube pre to my chain. I can imagine they would go well together.
As the others have noted going to the solid Bop mesh will also help tame the highs. I replaced the Bop mesh on my Aeolus with the vented Titan mesh and the highs were definitely more pronounced with the Titan mesh.
You're also on the right track introducing tubes somewhere in the audio chain. I run tube buffered NOS MHDT dacs coupled with full tube amps (Bottlehead Crack both with and without Speedball mod, Bottlehead Mainline, and Woo WA6) with my Atrium with great results. There is absolutely no harshness unless the recording is harsh to begin with.
I think you mentioned going with a full copper headphone cable. In my experience that will usually result in less pronounced highs vs a silver plated or full silver cable.