I demuxed the attack of the clones AC3 file from its VOB as it and TPM are the only 5.1EX DVD's I got. The demuxed wav has a good rich volume to it.
after I've then used either ac3machine or 5.1 soft encode to effectively mux it back into 5.1 AC3, the sound level has dropped dramatically which is a bit odd considering the source AC3 has so much more volume.
settings in soft encode were
512kbps AC3 DRC @ film:standard RMS value for dialogue normalisation -9db