Sorry to break this to you but the DD-1 is for noobs that think they are legit because they overpaid for a useless tool and a test tone that they could have just downloaded online instead of a CD and could have just bought an oscilloscope that does WAY more than just monitoring if you have distortion in your signal for way less than a DD-1. Not trying to be a d*ck by any means, just telling it like it is.
You also need to learn the relation of bass levels in the recording and how it directly affects your head unit's pre-out voltage which directly affects your amplifier power output and overall signal. Setting the gain and then leaving the volume at 38 out of 40 for every song you play is a one stop trip to clip city and blown equipment. Thats the worse way to set thing and run your setup.
Some music will have -7 db recording levels which already puts you past clipping, some will have -1 db levels of bass which will massively clip you. While some will have -15 db levels of bass where the song feels really weak. Thats why relying on a test tone to set gains for music is utterly and completely useless.
At least now you have a reference point where you stink up the subs, back down the gain or sub level until it doesn't stink or overheat your coil or amp. REMEMBER how loud that point is and now with each song you play you can adjust the sub level accordingly to match that level of output which is your ideal clean point.
Temperature, and knowing how loud your max clean output is via testing and adjusting everything accordingly per song played is called active gain setting which is what all the pros do. I'd advise you to download audacity, use the spectrum analyzer and see the recording levels of bass in several of your songs to get a feel of what you should actually be shooting for.
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ shows -3 db at 36hz which means if I set the gain with a -10 db tone, I'll be clipping by 7 dbs worth which equates to quite a few clicks to my sub level. However if I set it with a 0 db test tone, i'll be losing out on -3 dbs worth of output. which is a notch or two down on the sub level. Literally proof of why setting gains with test tones is utterly beyond useless.
Gear Temperature is important because 1: heat is what kills your subs and amps. 2: clipping causes heat. 3: you can be overheating because of other issues even though you arent clipping which will still kill your equipment.
