They don't support aptX, but Beats and others (the Sony 1000Xs, for instance) usually support AAC over Bluetooth which is similar in quality.

Not to bag on Rockwell, I appreciate his reviews and viewpoints, but do you trust that he has the requisite expertise to correctly analyse the quality of such an adaptor?

I... don't. His write-up doesn't inspire confidence either - I have no idea how he has performed the measurements.

I know enough to know that audio measurement is a very tricky endeavour, and most other measurements put the lightning adaptor's output at a few dBA worse in SNR and dynamic range than the iPhone 6S' jack output (but otherwise similar). Both are easily worse than a good external DAC. Certainly not "better quality" than the inbuilt option as Rockwell claims.

It's good enough for almost everyone, and is likely to be capable of higher fidelity than most source material, but most agree that it is objectively a worse DA.

And the DACs in older iPhones are equally good. Mr. Rockwell has reviews of those as well.