Problem with input monitoring vs. recorded track PT 10 HD

[Snowy]

hi, I'm noticing an unusual problem with the sound of Pro Tools input monitoring, compared the the sound of the playback of the same track after recording which I cannot figure out and am hoping somebody may be able to shed some light on this..

My setup: Mac Pro, OS 10.8.5 / PT HD 10.3.5 / 4 X Digi 192 / Apogee Big Ben
Session is 24bit / 48khz

I'm doing hybrid mixing; groups of instruments are bussed to stereo auxes, then those stereo auxes are sent to outputs of the 192's and to stereo pairs of faders on my analog console.

The master output of the console goes to a stereo compressor, then back into an aux track in PT where I do automation fades, some EQ and mastering style limiting.

That aux track is then bussed to an audio track in PT for the final print. I put that audio in input monitor and send the output to an "external 2 track input" on my console to listen back.

If I record a mix to that final print track and play it back, and then toggle "input monitor" on and off to hear the difference between the "live" mix and the printed mix, I can hear quite a difference between the two, with the printed mix sounding considerably better. The mix on input monitor sounds thinner in the bottom end, the kick is less punchy, the bass is thinner, and just generally doesn't sound as deep and solid as the recorded mix. It's not a massive, night and day difference, but it is definitely audible.

Has anybody ever experienced this? I've heard of people talking about the opposite problem - the recorded mix on playback doesn't sound as good as the live mix after another round of conversion... but I feel this is more a case of, the playback of the recorded mix is how it actually sounds, and the mix I'm hearing on input monitor is not correct. To me it sounds like some sort of phase issue, ADC not working correctly.

in Playback Engine, I have:
H/W buffer: 256
Host Processors: 7
CPU Usage: 90%
Voices: 192 voices (6 DSPs)
Delay Comp: Long
Cache Size: 5gb
Plug In Streaming: Level 2

It is a pretty full mix with a fair amount of tracks; some have plugins, some TDM, some RTAS, and some tracks have hardware inserts. I've tried changing both the HW buffer size, and the Voices setting, but none of that seemed to make any difference.

Hoping someone has some advice on this?!

thank you!

[cwsand]

Hi, Are you sure that what you're monitoring on the "external 2 track input" is all that you're hearing? As in, there's no amount of signal coming from any of the other console or Pro Tools channels out to your monitors? That could definitely make it sound phasey if there's a slight delay between the signals, and the amount of delay could change depending on whether you're in input monitoring or not.

[Snowy]

Hi Chris, thanks for your reply. You raise a good point which would definitely make sense.. I've double checked my setup, both on the console and patchbay, and in my Pro Tools i/o, and I cannot see any way that the signal is being duplicated or sent anywhere other than where it should be..