How to decode 6-track APTX-100 (cinema DTS) with the correct channel levels

[little-endian]

[...]once the A->D conversion has taken place[...]

You mean "D->A" conversion, don't you?

[zoidberg]

Yes, well spotted

[Dr. Cooper]

Yep, use 32-bit floating point PCM instead in Foobar's export settings and attenuate the levels in an audio editor of your trust. This should avoid the clipping.

Just using "32-bit Float" in the Output Bit Depth-settings in the converter-settings should solve it? Right now it's just set to "Auto" and converts the files to 16 Bit WAV-files.

And just to point it out again, so there's no confusion: It wasn't the LFE that was clipping, it was one of the Surround-channels (IIRC Surround Left).

[little-endian]

Just using "32-bit Float" in the Output Bit Depth-settings in the converter-settings should solve it?

Exactly. As I noted a few pages back here.

Right now it's just set to "Auto" and converts the files to 16 Bit WAV-files.

Yep, and that often leads to clipping.

For the LFE, you'll also notice that you often can't raise that by 6dB without causing clipping either. Better attenuate the rest accordingly (futher, the surrounds anyway).

And just to point it out again, so there's no confusion: It wasn't the LFE that was clipping, it was one of the Surround-channels (IIRC Surround Left).

Yes, since the LFE needs quite some boost anyway, it will most probably never clip during the process (may have some clipping baked in the mix however).