Same. There's a difference in texture, primarily in the trebles, but there's also a general muddiness and lack of separation. Everything feels like it's been smoothed over, but not in a good way, or too "crunchy". Transients don't have the right amount of bite and the stereo image doesn't feel as three-dimensional. It's harder to hear the "room". Currently using Sony IER-M9 with a Linum DualBax Zebra, which is a great cable, btw.

I feel like if I was playing Audiophile Bingo, I'd just have won.

I mean I can't claim complete 'ignorance', I have more audio toys than many (a "Schiit Stack" on my desk (DAC, mixer and amp) and a couple of "low end" headphones, Sennheiser and Hifiman planars), but by the time you are discussing cables... next thing it's whether wood volume knobs will eliminate unwanted resonances from your sound stage.

Favorite comment I heard on such things: Music lovers buy equipment to listen to their music. Audiophiles buy music to listen to their equipment.

I can too, but only because AAC has such an unnatural stereo presence that I can pick it out in a lineup of codecs with my eyes closed. If it was a direct comparison between downsampled FLAC/WAV then I'm not sure I could tell the difference.

Have you done any blind listening tests? I'm having a hard time believing this, though it depends on the bitrate of the AAC.

I do blind tests multiple times a day.

On cellular on my iPad/iPhone I stream at AAC and then high-res lossless on WiFi.

When the stream switches the improvement in clarity and sound stage is very apparent.

That's doesn't sound blind, if you don't have a very fancy setup that can switch to the lossless stream without any interruptions.

I simply have to press stop and start (which you can do many different ways) and the stream will switch.

Pretty fancy I know.

That's not blind.