OK i realise that i'm probably going over old ground here, but i note that the Blaupunkt 937 HU fitted to my 147 has no line level output for an external amp.
I've already fitted my Infinity components in the front doors (that was fun!) since the standard speakers are utter sh*te, and basically produce nothing from about 10KHz upwards.
The mid-bass is less pronounced, but that is good since the standard paper cones are very boomy. You can actually hear that there's something going on around 50-60Hz now. Amazing!
The downside of the Infinities is that they need a fair ammount of juice. Generally 30Wrms is about the bare minimum. I beleive the 937HU has an output of around 17Wrms per channel, which is OK for a 4" full range driver, but clearly not enough for the components.
So the question is how to add an amp. Speaker level inputs are a source of evil and should be avoided at all costs. Last resort if all else fails but otherwise you're compromising your nice amp with the audio performance (high THD, poor staging, restricted freq range etc) of the naff power amp built into the HU. Not good.
I've heard of people fitting pre-out's to their HU's, and i've done this myself in the past when younger and short of cash! If there is someone out there who knows how to best get a pre-out can we please have a guide? I'm sure there are a few other idiots out here happy to take soldering iron to board..
All rather frustrating as i have a lovely Alpine MP3CD HU with 3 line outs and all the bells and whistles, but fitting it would spoil the look of the dash... Damn Alfa for making the car look so good...
Thanks in advance for any help.