This is strictly a hardware issue, it's not Sonar's fault, but I've gotten so much useful help from the nice folks here, I was hoping someone has had similar issues and found a solution. Here's what's going on. I have a Line 6 Pod Pro HD and a Roland Quad Capture. The Pod has a great feature that allows you to monitor the Pod with the analog inputs and use the digital out to record a dry track while you hear the effected sound. I like doing it this way because there's zero latency because the Pod is doing all the heavy lifting. Once I have the dry track recorded, I can go through my assortment of amp sims and pick the right one for the job. However, the two device's clocks have to be in sync and up until lately there hasn't been an issue. But now, the Roland's clock sync alternates between internal and external (there's no way that I know of to lock it on external). This causes dropouts and the transport to stop sometimes. I have to unplug and replug the connections, or sometimes disconnect the usb and re-plug in and it will behave itself for awhile. I've searched forums for a solution and I can't find anyone with a similar problem. I was considering replacing the Roland, but finding a reasonably priced interface with SPDIF in is not easy to find. It might be the POD, it might be the Roland, I don't know. Any ideas?

I can't help with your Roland issue, but you might want to take a look at devices in the class of the MOTU 4pre (or 8pre if you need a lot more). You don't say what your budget is so I don't know what reasonable means to you, but it has spdif in and it's a reasonable price (around $450 USD). I use a rather ancient 8pre that still works wonderfully well, although it's not a latency king by any means, it sounds great and it never burps, ever. 
 
Good luck!

The MOTU looks like a nice piece, no MIDI though, it appears that is an $additional option. The thing is, it might not be the interface, it might be the POD.

This has midi.

I run the audio from my Pod Pro HD into Sonar via the balanced analog outputs - never used the digital outputs for this.
 
There's a dedicated analog out from the Pod labelled Dry Out. nothing wrong with using this TBH

I run the audio from my Pod Pro HD into Sonar via the balanced analog outputs - never used the digital outputs for this.
 
There's a dedicated analog out from the Pod labelled Dry Out. nothing wrong with using this TBH