Just a thought for a brand new unit, I’d discuss your experience with your sales rep after confirming all cables/PCs, etc are firmly seated. I have no experience with the Air Lens, as I went with Innuos. The Innuos is quiet as a still cold clear fall country night.
FYI, from what @Elk has posted in the past PSA tech support typically does not check the forum for customer questions or requests for technical support. There was a time when Ted did, but he’s been away from the forum as he’s working on the DSD Mk2 FW upgrade. Also, Ted’s focus is DSD FW questions. If forum members that have an AL don’t provide suggestions to a solution your best avenue is a call to technical support followed up with an email to ensure your question does not fall through the cracks. Just trying to provide some meaningful guidance.
I would check the DIP switches on the bottom of the AirLens. They are supposed to come from the factory all in the up position, which is appropriate for PSA DS DACs. If you have another brand they might need changing. See the manual for the settings involved.
I just played two DSD files (one 64, one 256) via the AirLens to my DS Mk2 and heard no crackling sounds.
When I first got my PST, I was using the PSA-supplied HDMI cable that I got years ago; it looks identical to the one that came with the AirLens, although I can’t comment on the internal construction. I found that upgrading this cable made a noticeable improvement, which would match your description of it as slightly muffled.
Right now I am using a Tubulus Concentus I2S cable from the AirLens to the DS Mk2 (paired with a Tubulus Concentus power cable to the AirLens). I am pleased with the TC I2S cable ($700), although I haven’t had the opportunity to compare it against the really expensive AudioQuest ones. No noise issues and overall very good SQ.
Note that this cable presents one slight issue: the HDMI connectors are slightly larger than usual. If you plug it into the AirLens or the DS DAC I2S outlets, it won’t seat properly because it bumps into two round-head screws that are close to the outlets. You just replace these with wafer-head screws, which I had no problem doing.
Edit/Addendum: I have a sneaking suspicion that this is a Roon issue (strange that a cable change fixed it, though). I know you said you tried the various settings with no change. But software like JRiver and Roon do things behind the scenes that are sometimes hard to ferret out (one of the reasons I don’t use them). Maybe some other Roon users can help.