Audio problem

[bibbys0]

I have just got myself a 406 3.0 exec w reg saloon which i love but heres the problem when i got it the radio didnt work problem was solved by changing the fuse which had blown on the radio itself.After changeing the fuse i get very low volume for the rear speakers only heres what i have discovered and checked
fuses all seem ok
in boot theres a jbl amp tucked under sat nav
radio functions apart from no volume (well even turned up full you can just to say hear it through rear speakers)
tried altering fade no difference

so I have come to the conclusion its either the radio or amp but am reluctant to replace either untill i know which needs replaceing.
Does anybody know if the amp has any fuses other than the one in the fuse box or
can anybody offer any solutions tests I can do to help eliminate or confirm that the amp or radio is faulty
I dont mind getting a replacement amp or radio of fleebay but would rather only have to replace one or the other
thanks for reading this and any suggestions are greatly appreciated

[Captain Jack]

I remember my dad having the same problem in his 405 but the radio needed a code. Even so, very faint sound was coming through. When you turn the volume right down, do you get any sound then?

Maybe whatever blew the fuse also broke something else?

[lozz]

Have you checked theres power getting to the amp?
if its the amp thats failed id just by-pass it,

[Captain Jack]

You can't by-pass the amp as the radio only has pre-amp outputs....

[lozz]

ithought all the radios where the same ?

also seen amp by-pass iso kits in halfords, or are they just for fitting aftermarket radios?.

[Captain Jack]

After market. You can replace the JBL amp with your own if you wish but it requires some rewiring. Better yet, replace the whole lot (although JBL system is pretty good for a factory installed system).