no sound from 2nd head unit

[larkins666]

Hello,i hav a honda accord 7th gen i-cdti. ive installed an after market stereo and had it working for a few months but when i tried to install a new amplifier i may have had the wiring slightly wrong and there was a noise from the speakers then nothing.

I have disconected the amp and returned to how it was working before, power is on but still no sound, although when i plug the origanal headunit back in everything works fine.
I then thought it must be headunit so have bought a new one but still have no sound.

As it has the premium sound system i believe(not sure) it has a power amp already but is not turning on with the aftermarket unit only.
I have also checked with a multi meter that all the wires are making a circuit and all seems to be fine there so im now at a loss and scatching my head alot.

Im wondering if theres a relay or hidden fuse, or somthing to do with the cpu or somthing, does anybody know anything at all about this or could even tell me where the power amp is or should be located.
Any info would be much apprieciated as this is a mystery to me, Thanks.

[basicxj]

Would you like your post moved to where someone other than a spambot might rear it?

[jepalan]

Are you using an off-the-shelf aftermarket adapter to wire the new head unit into factory harness? If so, which exact brand/model Metra? Scoshe?

[larkins666]

yes its an off the shelf harness but im unsure of the actual brand.
ive just bought and tried a new wiring harness, same problem, no sound at all, not even a crackle, its as if the amp is not powering up anymore, although it still powers up with the original head unit.
just out of interest, what differance would the brand make?