After market head unit RCA line out to speaker wire bose amp
The bose amp is very unique, its source needs to be low-level (balenced) signal over speaker wire. Most head units produce the normal high-level (unbalenced) signal. Not only are you get double amplification from head unit and again amplifying from amp (you can imagine how this tears up the sound) the signal has to be also corrected to a balenced output. The OEM 2 corrects this taking that unbalenced high level then passing through it, taking it down to low level (balenced) and feeding the bose amp its proper low level balenced. It sits inbetween the head unit and amp.
I know of alot of peope that just hook there HU directly to there bose amp. Sure it sounds OK but it can sound 100x better if you correct the sound output with the OEM-PAC2, its night and day difference. Id highly recommend buying this unit and placing it inbetween your amp and HU (its only $15). The bose system in our cars sounds awesome, just needs extra work to get it hooked up right. Hooking it up <b>without</b> the OEM-PAC2 is going to lead to early distortion and lead to unsatifying results, most like blaming that the bose system sucks and its lack of bass. I had it hooked up without the pac and i was gonna redo everything new amps and speakers....it sucked without it. With the Pac2 success im happy and did not have to change the amp or speakers.
Last edited by GiZzO; Nov 26, 2009 at 02:56 PM.
Since my head unit has 4v outputs I don't see why they can't just go straight in with proper grounding. Is the noise just from a ground loop of some type?
Edit: Is it something where the signal is on one of the two wires, the inverted signal on the other, and then the system just expecting the exact same ground on both sides for the third?
Last edited by Tamerz; Dec 11, 2009 at 05:49 PM. Reason: Added more thoughts.
But what im sure of is the OEM-2 takes the speaker feed from head unit thats high level to low level. The bose amp wants a low level over speaker wires.
I've tried hooking the HU in 3 configs to Bose amp.
1. No Pac (over amplified, early distortion, constant hiss)
2. RCA HU -PAC- low level bose (low volume, sounded great)
3. high level HU -PAC- low level bose (sounds great, proper volume level)
Using a RCA side is just another option. If its not balancing the signal, hey $12.50 for a line converter is not a bad deal.
Furthermore I just installed a new kenwood headunit in my c280 the unit is 4v. I tried hooking it up RCA from head -PAC- then low level speaker to bose amp. Again volume was too low. So I hooked it up the same way as my CLK (high level to low level speaker for PAC). And had full adjustment of the volume gain on the PAC hooking it up this way.
Its was nice having the flexability going RCA or speaker feed, since RCA low level didn't work even though it was 4v this run.
Last edited by GiZzO; Dec 12, 2009 at 04:31 PM.
I am a French Guy, ans just bought a 2002 CLK 320 w208 with Bose AMP.
Here is my ride:

I want to install a Pioneer F700BT in it. I know that the BOSE Amp Does not simplify my installation

If i understand well, i need the PAC2, no problem with that. My problem is to connect all that to the BOSE AMP. I know it is in the rear trunk If i am not wrong ? Did you uses wire from front to rear ? And does anyone has a wiring diagram for connecting it ?

Thanks for your reply.
The Best of Mercedes & AMG
I thought i have to run wire to Rear trunk...
Happy not to have to. 
I am trying to find a PAC OEM2 (or like) In France, but i can't find it. I have found an equivalent in Germany, (but without Low Level Line IN) especially made for BOSE system (what the vendor said). In fact it acts the same way the PAC OEM2.
If it works, i'll gave the ref.
Thanks for your help.
It's that:

It's the same as the PAC2, without the low level entries. Enough for BOSE.
I conneted all in my CLK and it works perfectly.
Thanks you to all of you for help.
I've tried hooking the HU in 3 configs to Bose amp.
1. No Pac (over amplified, early distortion, constant hiss)
2. RCA HU -PAC- low level bose (low volume, sounded great)
3. high level HU -PAC- low level bose (sounds great, proper volume level)
Using a RCA side is just another option. If its not balancing the signal, hey $12.50 for a line converter is not a bad deal.
Furthermore I just installed a new kenwood headunit in my c280 the unit is 4v. I tried hooking it up RCA from head -PAC- then low level speaker to bose amp. Again volume was too low. So I hooked it up the same way as my CLK (high level to low level speaker for PAC). And had full adjustment of the volume gain on the PAC hooking it up this way.
Its was nice having the flexability going RCA or speaker feed, since RCA low level didn't work even though it was 4v this run.
Goes back to your question is the PAC sending out a balenced signal. If not; then yes i've tried it this way cause then the PAC would just be doing line conversion, and i would have done it in the config your suggesting

Its $12.50 who cares it works and gave me options to go speaker level w/ individual gain controls, which i did cause volume was to low over RCA.
Last edited by GiZzO; Feb 6, 2010 at 04:46 PM.
Celts, can you tell us where you found this and whats its called?
Goes back to your question is the PAC sending out a balenced signal. If not; then yes i've tried it this way cause then the PAC would just be doing line conversion, and i would have done it in the config your suggesting

Its $12.50 who cares it works and gave me options to go speaker level w/ individual gain controls, which i did cause volume was to low over RCA.
If you're changing head units, it's possible to retain the steering wheel controls, but it depends on the head unit. What brand is the new head unit, and what model?
I know I will need to do some custom wiring with the use of an aftermarket harness I assume? That is what I currently have the clarion hooked up to but SQ is not good.
Someone that has done this, instructions appreciated

Anyways I am a bit confused on how I hook this up. Do I pull out the rca plugs and put in the extra wire set that it came with (pictured), therefore not using rca's at all? Or does it go RCA's from HU to Pac RCA's then Pac wires to VW Harness? Please give me some help on this one, thanks.
The PAC goes right after your HU. In other words, hook up the PAC using the wires on the harness it came with. The RCAs are only needed if you are using an aftermarket amp. ARE you using an aftermarket amp? Sorry if I missed this somewhere...











