re dbx alignment, (at least for dbx type I)
dbx type I is a 2 to 1 compander that adds pre emphasis to the record signal before the compressor and de emphasis on the playback signal after expansion.
Calibration of the tape machine was critical. Any error in the tape machine's record to play alignment was doubled. Because of the pre emphasis, you had to be very conservative with the level going to tape. The more you slammed level to tape, the murkier it would sound after decoding. In their operation manuals, dbx cautioned users that the loudest program peaks should never exceed 0VU record levels.
Unlike Dolby NR, dbx NR works the same on the quietest to loudest signals.
The only reason the dbx units had cal pots was for unity gain.
You could use a dbx decode unit that is many dB out of alignment.
Unless it's input is being clipped, aside from level matching being off, there would be no error in the decoding of the signal.