Hi W
I only have the 7 speaker system so no sub. There are two separate (line level and speaker level) sub outputs from the head unit if needs be. However looking at the pinouts on the Denso unit, there's no separate sub line out so I suspect the sub output is derived by the amp so you don't need to worry about it. sgould has the 8 speaker system so I'm sure can confirm.
The head unit has both speaker level and line level outputs.
Originally I wanted to use the line level outputs as that's what the amp is expecting. However 2 points - one it involved cutting the existing wiring loom and somehow connecting the twisted pair line out cables from the head unit to the wiring loom, via isolators. Doable but added work. Two I was advised that there would be less interference using the speaker outputs as on the cheaper units the line outs are unlikely to be properly isolated inside the unit.
The loom I've used takes the speaker outs and via a "preamp" (basically a set or variable resistors.) brings that level down to line, goes through an isolator for each channel and thus outputs to the amp line level.
The pots are the variable resistors. When you first fire up the unit have them turned down as low as they'll go. I then set the volume on the head unit to about 3/4 of max, played an mp3 track (or tune the radio to a station.) and turned the pots up in turn until they reached a decent level. I then edged the head unit volume up towards max and made sure the level wasn't going to high (no distortion.). Personally I've left quite a lot of headroom as I was worried about overloading the speakers.
As there is a pot for front L/R and rear L/R you need to balance them. I spent some time going between the front and back seats. In the end the two variable resistors for the rear L/R were set a bit higher than the fronts two.
Hope this makes sense, I'm a bit tired so probably not explaining myself too well...
