When is a plug in not plugged in? And are DAW's more temperamental than we think? Two recent experiences were eye (or ear) opening to say the least. The first occured when I decided to re-order how the tracks appear in the DAW, merely to make things look more organized. I had already exported a wav file with the disorganized appearance, ordered the track in more logical groupings, and re-exported a wav file. Now I would swear they sounded different, very subtle, but different. I am willing to leave some small window of doubt about my observations of the above, but on the second part I am about to describe, I am positive. I had had a certain mix, and liked it. A few days later, during some experimentation, I made several changes to it, and inadvertently saved it instead of saving as something else, meaning that I changed a mix I did not want to change. I spent the next few days reverting the settings using notes, other versions of minor difference, and memory. Yet even after restoring everything I could identify, the mix was different, not bad, but still slightly different. But just now, I remembered one change I forgot to restore. In the first export, I had two plug-ins installed, a simple limiter and a mild high frequency boost plug in across the two bus, but I exported the file with the bypass switches on, meaning the effects should not be printed to the export file. On the version I was hoping to restore exactly, I did not have these unused plug ins installed. I thought it could not make any difference, but after laboring endlessly to get it exact, I began to wonder if they could indeed have an effect, even if they are bypassed and thus not functioning. I just installed the two plug ins, and bypassed them, and viola, I had the mix restored identically. It seems having plug-ins installed even if they are bypassed (and thus not functioning) will have a sonic effect. Of this situation, I am certain. Is this a known phenomenon? Any other thoughts? It is slightly distressing to think that a non-functioning plug in could have an effect, as it adds a whole new order to the already infinite combination of possible settings.