Sorry to bring this thread back but it's a great one
I've done a little research on adding a THA-275/475/555 to a basic BMW sound system and it seems the logical way to go however, this system doesn't come with tweeters which for the amp may cause problems i.e. burn out. Basically the way I see it is that if you install the THA-275 for example on only the factory front 4 speakers (x2 mids front, x2 under seat) it'll be fine and will run on 2ohms no problem BUT, add L7 or HiFi tweeters and you're running three speakers on one channel at around 1.3ohms which will burn out the amp. If this is the case then buying the THA-275 is pointless as you'd have to run the under seat subs from the rear channel and then front mids/tweeters on the front channel by using a 4 channel amp such as the 475 or 555. This would require cutting of the Blaupunkt PnP loom and therefore it's a pointless install, you may as well go aftermarket for it all, right? The rear speakers would be run of the HU as normal so don't come into the equation as such.
The other way to do this would be to run the under seat subs off of their own channel which again would require cutting of the OE loom connecting to the subs and new wire going to the amp.
Now that this install is tried and tested, how did people get on with that? Is it now deemed an nonviable option due to the above issue?
I'm upgrading to L7 tweeters and mids which will no doubt highlight the sh*t base, for that an amp is required...somehow but it looks as if that's only achievable in a non-PnP fashion or is there a way? I'm wondering if I'd be happy with L7 mids and an amp only as I never plan to upgrade the under seat subs.
On a side note, why do some of you run the THA amps from the battery and others directly from the HU? What are the benefits of running power from the battery if PnP power is catered for?
The way is see it is that this is a good PnP upgrade the OE system however, it can only be used if you don't add tweeters.