Upgrade Amp?

I've removed my stock BOSE head unit on my 2003 C4S and I'm not happy with how the new double DIN unit (Pioneer) works with the stock MOST BOSE amp. I'm looking for recommendations on whether an aftermarket amp will work with the stock BOSE speakers, and if so, what amps have people had success with? Since my car has two speakers in the dash, two in the doors, two in the back seats and the sub woofer will a 5 channel amp work with that or will I need something with more channels? I've also heard that the BOSE speakers are 1 or 2 ohms, so will I need to get an amp that is in that same ohm range? I'm not an audiophile, so this is not my area of expertise... that's where I'm hoping this group can help. Thanks!

The head unit in a 2003 with Bose speakers is a Becker product, not Bose. Likewise, the power amp is also Becker, I am fairly certain. It has no identification on it, which is not how Bose rolls. I replaced the head unit and power amp with Alpine products several years ago. Based on the number of outputs from the power amp, I disconnected the side speakers in the back, although they could have been run directly from the head unit, I think. They are not missed. The "subwoofers" in the back (actually a bandpass configuration) are one ohm each, IIRC, so you wire the two in sequence instead of in parallel, so as to provide 2 ohms of resistance, which is typical resistance for a sub. You can spend a lot of money replacing the speakers, and a lot of people do. I decided to begin with the power amp and head unit. Mine were dialed in nicely by the installer; i.e., crossovers and EQ settings, and I am very, very happy with the result. Good luck.

Since the main issues seem to focus around the amp, has anyone just bypassed the amp and connected the speakers directly to a new head unit? Does the Ohm rating on the speakers make it difficult or impossible? My new head unit seems to have plenty of power for my needs so if I can just bypass the amp, I'm up for trying that,

I have a 2001 996 C2 Cab that had the HiFi (i.e. non-Bose) system installed. I'm one of those guys that spent a lot on speakers and swapped everything out, including a modified Bose subwoofer box (bought off eBay) that fits in the passenger footwell. I went with a 5 channel amp that drives the dash and doors on 4 channels and then the sub off the 5th channel. I was able to drive the two rear speakers directly off my Kenwood head unit and am pleased with the sound. I know your situation may be different with the MOST system so you may need to get a unit that converts the signal to analog for speaker-level output. One source of info that I found invaluable is Rod Birch at Car Audio Innovations (cai-store.com) where he has plenty of how-to articles and will sell you everything from speakers and amps up to a complete system. Highly recommended.

I have very limited info on how the MOST system works, but know enough to know the output isn�t standard line level. My C4s had the most system, but a PO spent big bucks and installed all aftermarket components but the amplifiers installed were zapco DC series amps that work on a similar system as the MOST with symbalink cables instead of standard RCA cables. These are phenomenal amps and there are currently several available brand new on eBay. Do your own homework, but may provide a good solution to your issue, particularly if you plan to replace your speakers.

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Yea, I've done it in the past, but the sound is not as strong as when using a dedicated amplifier. I think the Bose speakers in the dash and rear are 4 ohms, but the door speakers may be 2 ohm. Might want to check that out before rewiring it. I don't think you're going to be pleased. You might want to replace the amp or first investigate the condition of the speakers. My OEM speakers were in horrible shape and so that might be your problem instead of the amp.

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I think you will have a wiring issue (the speakers are all wired to the location of the power amp in the frunk). You would have to either re-wire or extend the existing wiring from the frunk into the cabin. Keep in mind that the much-hated MOST harness is just between the head unit and the power amp. You have ordinary wiring from the power amp to the speakers. I think you would also be short some outputs from the head unit, depending on what you use. I disconnected my rear side speakers, but you still need three pairs in the front and a sub output at 2 ohms. A good power amp can be had for less than $300, no? This is how to really dial in the best possible sound to each speaker, IMO.

I'm thinking that I'm going to pull the trigger and just replace the amp. This will allow for me to get rid of the MOST connection issue and hopefully will also get rid of the alternator noise that is going through the speakers. I plan on using shielded RCA and speaker wire for this and getting a 5 channel amp. From what I've read, you can combine the cables for the door speakers and the sub which will allow the 5 channel to power all the speakers. These instructions are from the CAI-Store regarding this set up... Anyone try this???

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I don't think this is what I did. Not sure because of the reference to "floor" subwoofer, which sounds like something other than the Bose two 10" bandpass unit that comes as part of the Bose speaker package, that I have Someone with personal experience will likely check in, because that mod is not uncommon. The resistance issue is addressed there in a slightly different fashion, I believe. Regardless, you use a 5 channel amp. The tweeter/mid units in the top of the dashboard have their own crossovers, so you only need one channel for each. Strike my reference to needing "three pairs" for the front, in an earlier post. I wasn't crazy about the idea of sticking a sub either behind a front seat or in the passenger footwell, which seem to be the choices (and seem to be what is shown above, wiring-wise). Plus, I needed to be persuaded that the "stock" Bose rear unit is incapable of producing acceptable bass tones, given the right signal, before I got rid of it. AS previously mentioned, that unit works just fine for me. One more slightly technical point. If my assumptions are correct, the ported front door speakers described above must share a sub-woofer signal with a sub located somewhere in the car. Sub signals have very limited frequency ranges, and aren't stereo, IINM. My front door speakers have their own, stereo signals, EQ'd for low and mid-range sounds.

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I know this sounds like more work but have you thought about not using the factory speaker wires going from the amp to the speakers by running new wire and replacing door speakers with a two or three way component system and bypassing the dash speakers, using the door, rear quarter speakers on the shelf sub (since there isn't a better sub package)? As good as an addition an amplifier is those are some old speakers that won't be able to handle what amp brings as well as new speakers.

Because I couldn't recall the specifics of my switch (almost 4 years ago), I pulled out the file, which includes some stuff from the internet related to the project, and I want to confirm/correct some items. First, I was really surprised to see that the power amp is apparently a Bose product, according to two items from the internet. I guess this makes sense, given that the woofers (only one for a convertible, apparently) run on one ohm of resistance. This is very unusual and one of the challenges in converting. The photo above maybe was from an installation in a convertible? The two sub drivers in a coupe are 5 1/4", FWIW.

Does anyone know if there's a source for an adapter plug that would connect to the speaker plug that goes into the factory amp? I've found the PC2-95-4 ISO adapter, but it shows that it's for 2004 cars and I have an 03. This is what the adapter looks like.

The floor sub is in the Cab,, Not the Coupe.. They are different. Whatever you do make sure the amp is a HIGH current amp,, Rated for low resistance speakers. Bose speakers use current to pump the woofers. they are great IF you get enough power to them. The 2003 is a one hit wonder, From what I can find you need the Cayenne adapter for the 2003. As the 911 got the same stereo, because it was fancier,, all the other Porsche stuck with the Older unit till like 2004.

^ What he said. The Porsche drivers are very low resistance; you need a 2-ohm-stable amp. I used an Alpine PDX-5 to drive the factory speakers in my 986.