AAC/M4A File - Elements Distorting over Bluetooth

[nyaben]

I have been noticing tracks that contain distortion (only notice it in my car and it's usually electric guitars). One common element is that the guitars have sends to reverb. I don't think the return is too hot but I could try pulling it down (never had to baby it this much before if that is the cause here). I have yet to try the mixes sans reverb and sans guitars altogether. I don't hear it on other systems. I have tried lots of other trial and error approaches with none removing the distortion.

I've been very careful to mix (in all of these "tests") to an integrated loudness level of -16 LUFS with true peaks of no more than -0.9 dBFS (measured with db meter II plugin). Gain staging is not an issue in the individual tracks (having learned that lesson years ago) and I also am not aggressively limiting the tracks (using Elephant for limiting chores which is, given the settings I use, very transparent).

Using Reaper 32-bit for Windows on Windows 7 Pro, 8 GB memory, Dell Inspiron 620 (i5 processor).

"Car" versions are m4a/aac files converted from 24-bit, 44.1 kHz files using QAAC (iTunes) to produce 256 kbps VBR files (iTunes Plus roughly).

I ultimately found that these mixes translate fine in the car via flash drive/USB and that commercial artists translate fine via the same bluetooth connection.

Any ideas?

I never had this problem before January of this year.

[nyaben]

I wonder if it could be that I clipped the mic preamp I used and did not subsequently clip the recording into Reaper. Seems I'd hear the clipping on all monitors if that were the case.