aftermarket head unit too loud

[pieter3d]

I just had a car stero shop (Car Toys) replace my aftermarket Pioneer DEH 230 with an Alpine CDA 9851. They asked me if I wanted to bypass the factory amp but I said no, since I didn't do that with my Pioneer either.
The pioneer unit was a bit loud too, but this is way worse. The Alpine unit is uncomfortably loud at volume 9, which is only like a quarter of its max output.
Is there a way to attenuate the factory amp, or should I go back and have them bypass it (or can i do it myself)?

BTW: I have a 91 SHO with JBL audio.

 

[HoustinoJillian]

there's a simple wiring harness you can buy, search around for an amp bypass harness, and yes, it is easy to do.

 

[gospeedgo]

They probably used the high level outputs instead of the low levels. I talked to a local shop and they said thats how they do it and didnt know that the adapters for the ford harness are readily available. I made one, and it works great. Much easier on the jbl amp than piping high level in as well.

What did you do for the amp turn on wire? Our amps use a 5v signal, not a 12v. The shop I talked to also said they use the 12v "and it works just fine.." but I used a simple $3 5v regulator to be safe.

 

[DVJ38]

Wait, I'm confused is it too loud for you, or is it unclear somehow? I never would say it's too loud! I'm loving my Alpine 9843 with the JBL, still not loud enough, not enough bass. But that'll have to wait.

 

[pieter3d]

Finally got it fixed. Yeah it was too loud. The volume goes from 0-35, but 10 was already unbearably loud.
I got this attenuator box kinda like these ones: http://www.logjamelectronics.com/intfaceconv.html except it was $40. It quiets down the powered output so that the factory amp doesnt rail it.

I tried connecting the pre-outs to the factory amp but then the sub kept cutting out randomly. Turns out the pre-out level is too low for the JBL amps. Bypassing the factory amp would havel left the sub just sitting there, not doing anything, so this is really the best solution.