Hello everyone

Sorry for the wall of text, but this problem is messing with me real hard!
Just got myself a Fiat Punto Multijet 1.3, and i want to put an amp in the boot, so i can get a subwoffer and new speakers set up. This is proofing to be a big problem though.

First of all the radio doesnt have a PHONO output as i need for the AMP (pics attatched). I finally thought i had fixed the problem when i found this mini ISO -> PHONO adapter (pics attatched), but this didnt fix the problem either! I tried plugging in the adapter and hooking the phono cable up with my buddies amp and sub, and nothing happened.

Normally i would just have changed the radio, and gotten a frame for the new radio to fit the hole, but i cant seem to find any frames that fit this weirdly shaped hole. (pics attatched)

Any help at all would be greatly appreciated, i know that one of you must have hooked an amp up to this kind of car, im just hoping to get the attention of this person. Thanks in advance!