(Long) Update:
So I made the mistake which I mentioned previously, of molding the lightning cable in, before really trying everything out. It was originally planned in my head that I was going to run a head unit above the iPad, with that kit I posted in the first post. I set it there a couple times while driving, and didn't really care for how much space it would take up. Sure, I could make my own, but im not great at making something out of nothing, so I didn't really want to try, as I wanted to get this project buttoned up finally and have good working audio again.
I figured, cheapest route, I could just keep the double din I had (Pioneer AVH-X4700BS) and sink it back further to clear the iPad kit. That radio I believe is bluetooth 3.0 though, which means lag. Music is fine, but when it came to videos, theres a 1-2 second delay on the sound vs whats happening on the iPad. Its not a big deal, but it would drive me NUTS.
So I did some research, because I have many bluetooth headphones for work that have no lag when i'm playing Netflix or YouTube at work. (Bluetooth 4.0 and above appears to have no lag)
I had 3 options. Since the usb cable was already permanently in place, I was limited. The lightning cable has digital audio, not analog like the old 30-pin connector. What most people do, is buy a lightning to 30 pin adapter, and then the 30 pin to 3.5mm and USB. This gives you an audio connection, and a USB connection to get power from. This would've plugged into the USB charger, and then the 3.5 into the back of my EQ which is mounted under the vents. I planned on using the EQ to control the audio. (Volume, sub level, bass/mid/treb).
1. Buy a really expensive DAC which uses the lightning cable. They literally only have one, its been out for years, and its just under $200. This is a big unit that you plug the lightning USB cable into, and then another mini-USB to power it, and charge the iDevice, and then it outputs the sound through a set of RCA's which would plug into my EQ. Again, volume through the EQ.
2. Buy a bluetooth receiver that outputs to a RCA or 3.5mm and uses a mini or micro USB to charge/power. This was before I knew about the lag.
3. Buy a single din to mount in the glovebox, plug the iPad lightning cable directly into the head unit. Now head unit charges, and controls volume. Also have the option to listen to FM if I ever wanted to again, and have a bit more tweaking of sound.
So here's what I did today. I bought a mechless Pioneer deck (Mechless=no CD so the deck is about 4" deep, and weightless) and I also bought a nice little bluetooth receiver to try my other idea. Radio was about $75, bluetooth adapter was about $30. Still way cheaper than the $200 DAC, which I will explain why, later, i'm glad I didn't order.
I tried the bluetooth adapter in my house on a set of computer speakers with the iPad. It sounded great, and there was NO lag. Seemed like I had the perfect device. Audio quality loss seemed very minimal as well. So I went out, removed my old head unit, and rigged up the set up to run the bluetooth adapter and my EQ. For some reason, the volume was extremely low. It didn't sound bad, but full blast was about "highway with the windows down" listening level. Guess I could've adjusted my 4 channel amp gain higher, but I didn't want to do that, as it would start to let in white noise.
Bigger issue though, is that the EQ really pissed me off. It has a volume knob, and a sub level knob. In my eyes, and im sure yours, the sub level would be just like a head unit, set it to match the blah blah without clipping and such, and then your volume controls the master level. Nope. This EQ volume only controls the 4 speakers, while the sub stays at the same volume its set at. (Meaning if I turn both volumes halfway up, I have both bass, and music. If I turn just volume down, I have no sound from the speakers, but the subwoofer is still pounding)
So at that point I was pissed, knew I needed a head unit, and was glad I decided to buy one in the same trip from earlier. I forgot how TINY the 4th gen glovebox is, so basically I have very little room left, but it fit nicely. I have extended the power and remote wires and ran them, as well as the (single) RCA's to the EQ. This bothered me at first, having only one set of pre-outs, but the EQ only takes one input, and splits them to a front/rear/sub, so it worked out. I have also ordered this:
That will allow me to completely disregard the head unit, and not have to touch it. It has a nice remote control, but of course the remote doesn't work with the glovebox shut. I can mount this IR extender and hide it, and have full function with the remote, which will control the volume. Best part is I will also be able to control play/pause/and skip forward and backwards tracks on the iPad without touching it.
So, the EQ now, is just that; an EQ. Its nice though to have sub control, as well as all my frequency controls as I listen to a large range of music and constantly adjust it on the head unit.
Here is a quick video, its dark, but I got everything set up and working exactly how I want it! I will have better video(s) tomorrow or Monday once I button everything back up and get it completely put back together!