Odd Audio Problem. DSP or Head Unit?

I've been in the car audio scene 25 years and this is the strangest problem I have ever seen. The system consists of (in signal order) Kenwood DNX891HD head unit, AudioControl Matrix line driver, AudioControl DM-608 DSP, Audio Control LC-6.1200 amp, Focal components and a JL 10W3 sub. The problem, is the sound constantly changes. I can set a nice RTA curve, fine tune the DSP, and within a few days, it sounds bad again. I take another RTA reading to confirm what I am hearing and the frequencies are all over the board again. Some are up and some are down, and I have used pink noise and static frequencies to do these checks. I think it is also important to note that I have used pink noise from a CD, an ipod and some generated from my RTA app, so even the sources are different. I have been working with AudioControl for the past month on this issue, and I have yet to get it fixed. They don't understand why their DSP would do this and I have been sending a ton of proof and we've been working together to figure it out. Their customer service is top notch, but I am starting to think that even though I am using their DSP to tune with, the actual problem may be with my head unit. The head unit is only 3 years old and was not cheap. All of the EQ/DSP and other audio settings in the head unit have been bypassed so the AudioControl DSP can manage it. At this point, I am waiting for AudioControl engineers to look at some things in the file I sent them, and I am sure I will be sending the unit back to them for further investigation, but I don't think they will find anything. Has anyone experience anything like this before? "Drive it like you stole it"

No, I've never seen this before, but I agree with your diagnosis. Either the HU or the DSP is not holding its settings. When it changes, does it got back to the same default settings every time, or is it random? If random it could be heat related. If the same or close to the same then it sounds like a memory error. I suggest making sure you are not being tricked by a signal from the vehicle harness. If you haven't already run clean power for the HU (including retained power) and the DSP from the battery, and don't use any of the vehicle signal logic.Support the12volt.com