Okay so here are the vitals: Windows 7 UltimateX64, Echo Mia Midi audio interface, Sonar X1C Producer.
Here is the problem.  I just got the Echo Mia Midi audio interface. I take midi files and using soft synths create more realistic audio and then export each part separately into a mixing project.  I have done this for years and never had any sync problems with my old sound device. Since I started using the Mia Midi the tracks sound better but for some bizarre reason the exported audio tracks are out of sync by as much as 70 ms.  The files are all exported as WAV at 44.1/24 bit and imported to the same starting point, as I have always done.  The Mia midi latency is much lower than my previous sound device.
I am stumped.  I have rerecorded several times and the timing is different each time.  I haven't even gotten past bass and multi-tracked drums because it is so hideously off.  Correcting it manually on each track is out of the question because the project will end up with 22 tracks. I have messed with every setting I can think of that will effect the timing of an individual track during recording.
Has anyone ever experienced this?  Can anyone suggest a way to fix the timing issues in the actual recording process?  I am sure it has to do with the actual recording and not the importation into the project.  Please keep in mind the timing is perfect on the midi file and I have been doing projects like this for 6 or 7 years without issue.  It only started when I started using the Echo Mia Midi.  It sounds great but I am completely stumped about the sync issues.
Thank you in advance.

Why not X1D? You should have the latest patch. 

Are you using more than one soundcard? That can cause timing problems. 

Are you using a USB microphone? Sonar treats those as soundcards and could cause timing problems.  

Well I updated to X1d but there is absolutely no difference. I have a usb camera but it is currently disabled. I only have the one sound card. Any other ideas?

Are your sync clock settings all correct? If you just bought the MIA contact Echo and ask them. I'm sure they have support.

Also make sure you have the most up to date drivers from Echo (and all of your devices for that matter). May not be an issue but it's always a good idea. Welcome to the forum.

I noticed a error in my original post. The WAVs are being exported at 44.1khz and 32 bit depth. I don't think that would make a difference but I am not ruling anything out. I contacted Echo and they had me check out the WDM driver and ASIO4All. No difference at all which is weird. The end result was they think it is a Sonar settings issue. I have completely uninstalled Sonar and wiped out any vestige of the program on my computer (including a deep search in the registry) and then reinstalled. I tried again and now the bass track is ahead of the drums by about the same amount. @#$%%????. I don't get it. It is definitely a Sonar settings issue but I can't think of a setting I haven't fiddled with. Does ANYONE have any other ideas?

I'm not sure I understand your workflow.  Why do you need to export the WAVs to a different mixing project at all?  Why not render them inside the current project (ie., bounce to tracks), save the project with a different name (project1-NOMIDI.cwp) and then remove the MIDI/Instrument tracks and then start mixing there?

I noticed that about X1, when you're working in 16bit, the dialog to export comes up set to 32bits. It should default to the project bit depth.

You might try exporting a count with the wav's, and get the bit depth right just to help sync up things.

What program are you mixing with?

Bit  rates will not be causing sync issues however sample rates will.

Try bouncing the synth tracks to audio first in the creating project ...then... export that audio file. It should have the complete track. I have seen where exporting the output of a synth that comes in at measure 4:2  for example exports without the info between the start of the timeline and the start of the music.... so lining it up later is an issue. 

Another option is to do ALL the work from tracking to mixing in the same project.  save all that exporting...... and mix it in the project. If it is all synths simply freeze or bounce them in place....then..... when you export, use the preset called WHAT YOU HEAR after selecting all the tracks and you save a ton of work. 

I use the method of do it all in the box and in the one project.   I also want to say I use 16/44.1 to export and record 24 bits @ 44.1khz