Hey guys! I've posted about this a few times, and since then I've changed setups, invested in a power conditioner, bought hum/ground loop eliminators and switched audio interfaces. The problem is still the same, and it's one I used to get even with the XT Pro and X3 Pro.

Basically I can run dry guitar back into my HD Pro by SPDIF with no problem (I track dry guitar into my sequencer using the dry guitar analog out, and it works just fine). However this means I'm using two analog inputs on my audio interface, when I should really only be using one. If I connect SPDIF in and out at the same time, I cannot get sync lock, as though both devices are battling for master status. What's more, if I connect the HD Pro as clock source, SPDIF lock frequently gets knocked out by the slightest of things like a light turning on or off in the house. I would be inclined to suspect bad wiring but I also notice that disengaging the tuner causes a similar effect, not to mention the fact I've had this happen across multiple computers with both my old FireWire interface and my new one (both M-Audio).

I'm receiving a USB2 interface tomorrow - Komplete Audio 6 - so the first thing I'll do is see if it's any different with that, but I have seen other posts online relating to users being unable to connect SPDIF in and out at the same time. What are your experiences??

My full setup is as follows:

Samson PS10 Power Conditioner (into which I run absolutely everything)

Belkin Surge Protected Mains Strip

Desktop Computer (Phenom II X4 965BE, 4GB RAM, 750W Fatality Gaming PSU)

M-Audio ProFire 610 (previously FW410, same problem)

Behringer HD400 Hum Destroyers between all analog connections

POD HD Pro

The only component I'm not 100% on is the FireWire controller, although I have no issues with the connection, no audio driver dropouts or anything like that.