Hardware = finished; Software = eh...

So I got the inverter chip (TC962EPA) which inverts any input from +3 to +18V and wired it up so it's giving the Saablin board the -12V for the OpAmps....it works great! The ground loop isolator made the sound quiet, and a little hollow, and seemed to miss some lows (although it shouldn't have according to the specs). Rass' Saablin board with the opamps sounds a little hollow, but the lows came back, and overall, it sounds wonderful :)

Rass' website here: http://saablin.net/
Rass' Saablin Balanced Audio circuit board: http://saablin.net/node/10
BatchPCB board for order: https://www.batchpcb.com/product_info.php?products_id=31438&check=04c8d356c127174ce72449dcbc8523ce

I still need to update my entire diagram to replace the dual ground loop isolator & replace it with Rass' Saablin board.

As for the software....it still has the display glitch that flickers "BlueSaab" with "CD1 Play".

// ----------------------------------------------

// SECUDUINO

// http://secuduino.blogspot.com/

// By Igor Real

// 16/05/2011

// 

// Saab CDC Changer Emulator

// http://BlueSaab.blogspot.com/

// By Seth Evans

// 4 Oct 2012

// ----------------------------------------------

#include <CAN.h>

int cdbutton;

void setup() {

  // set up CAN

  CAN.begin(47);  // Saab I-Bus is 47.619kbps

  Serial.begin(115200); 

  cdbutton = 0;

  CAN_TxMsg.header.rtr=0;     // this value never changes

  CAN_TxMsg.header.length=8;  // this value never changes

}

void loop() {

  CDC();

  delay(5);

  if (CAN.CheckNew()) {

    CAN_TxMsg.data[0]++;

    CAN.ReadFromDevice(&CAN_RxMsg);

    //PrintBus();

    if (CAN_RxMsg.id==0x3C0) {

      //CDC();

      //delay(5);

      if (CAN_RxMsg.data[0]==0x80) {

        switch (CAN_RxMsg.data[1]) {

        case 0x24:

          cdbutton = 1;

          Serial.println("CDC");

          break;

        case 0x14:

          cdbutton = 0;    

          Serial.println("Radio");

          break;

          //case default:

        } // end of switch case

        //else if (CAN_RxMsg.data[0]==0x80 && CAN_RxMsg.data[1]==0x14)

      }

    }

  } 

  if (cdbutton==1) {

    //CDC();

    //delay(5);

    iPodOn();

  }

  else {

    iPodOff();

  }

}

void CDC() {

  CAN_TxMsg.id=0x6A2;     // 

  CAN_TxMsg.data[0]=0x32;

  CAN_TxMsg.data[1]=0x00;  

  CAN_TxMsg.data[2]=0x00; 

  CAN_TxMsg.data[3]=0x16; // 

  CAN_TxMsg.data[4]=0x01;

  CAN_TxMsg.data[5]=0x02;

  CAN_TxMsg.data[6]=0x00;

  CAN_TxMsg.data[7]=0x00; // 

  CAN.send(&CAN_TxMsg);

  delay(5);

  

  CAN_TxMsg.id=0x3C8;     // CD Changer

  CAN_TxMsg.data[0]=0xE0;

  CAN_TxMsg.data[1]=0x00;  

  CAN_TxMsg.data[2]=0x3F; 

  CAN_TxMsg.data[3]=0x31; // playing disc 1

  CAN_TxMsg.data[4]=0xFF;

  CAN_TxMsg.data[5]=0xFF;

  CAN_TxMsg.data[6]=0xFF;

  CAN_TxMsg.data[7]=0xD0; // married "OK" code

  CAN.send(&CAN_TxMsg);

}

void iPodOn() {

  CAN_TxMsg.id=0x328;     // SID audio text

  CAN_TxMsg.data[0]=0x42;

  CAN_TxMsg.data[1]=0x96;

  CAN_TxMsg.data[2]=0x02;

  CAN_TxMsg.data[3]=0x42; // B

  CAN_TxMsg.data[4]=0x6C; // l

  CAN_TxMsg.data[5]=0x75; // u

  CAN_TxMsg.data[6]=0x65; // e

  CAN_TxMsg.data[7]=0x53; // S

  CAN.send(&CAN_TxMsg);

  delay(5);

  CAN_TxMsg.data[0]=0x01;

  CAN_TxMsg.data[3]=0x61; // a

  CAN_TxMsg.data[4]=0x61; // a

  CAN_TxMsg.data[5]=0x62; // b

  CAN_TxMsg.data[6]=0x00; // _

  CAN_TxMsg.data[7]=0x00; // _

  CAN.send(&CAN_TxMsg);

  delay(5);

  CAN_TxMsg.data[0]=0x00;

  CAN_TxMsg.data[3]=0x00; // _

  CAN_TxMsg.data[4]=0x00; // _

  CAN_TxMsg.data[5]=0x00; // 

  CAN_TxMsg.data[6]=0x00; // 

  CAN_TxMsg.data[7]=0x00; // 

  CAN.send(&CAN_TxMsg);

  delay(5);

  CAN_TxMsg.id=0x368;     // enable the SID (audio) text?

  CAN_TxMsg.data[0]=0x02;

  CAN_TxMsg.data[1]=0x19;

  CAN_TxMsg.data[2]=0x00;

  CAN_TxMsg.data[3]=0x00;

  CAN_TxMsg.data[4]=0x00;

  CAN_TxMsg.data[5]=0x00;

  CAN_TxMsg.data[6]=0x00;

  CAN_TxMsg.data[7]=0x00;

  CAN.send(&CAN_TxMsg);

  delay(5);

}

void iPodOff() {

  CAN_TxMsg.id=0x368;     // turn off the SID (SPA) text

  CAN_TxMsg.data[0]=0x02;

  CAN_TxMsg.data[1]=0x19;

  CAN_TxMsg.data[2]=0x00;

  CAN_TxMsg.data[3]=0x00;

  CAN_TxMsg.data[4]=0x00;

  CAN_TxMsg.data[5]=0x00;

  CAN_TxMsg.data[6]=0x00;

  CAN_TxMsg.data[7]=0x00;

  CAN.send(&CAN_TxMsg);

  delay(10);

}

void PrintBus() {

  if (CAN_RxMsg.id==0x290) {

    Serial.print(CAN_RxMsg.id,HEX);

    Serial.print(";");

    Serial.print(CAN_RxMsg.data[0],HEX);

    Serial.print(";");

    Serial.print(CAN_RxMsg.data[1],HEX);

    Serial.print(";");

    Serial.print(CAN_RxMsg.data[2],HEX);

    Serial.print(";");

    Serial.print(CAN_RxMsg.data[3],HEX);

    Serial.print(";");

    Serial.print(CAN_RxMsg.data[4],HEX);

    Serial.print(";");

    Serial.print(CAN_RxMsg.data[5],HEX);

    Serial.print(";");

    Serial.print(CAN_RxMsg.data[6],HEX);

    Serial.print(";");

    Serial.println(CAN_RxMsg.data[7],HEX);

  }

}