how long a cable are people using for head unit to amp mounted in the boot?

after 4 years i finally find out my RCA cables are cheap and crappy, so i'm looking to buy a new one. my existing cable is way to long - have about 3 ft coiled up in the boot, and short of removing it, i dont know it's length to guestimate from.

any sugestions for cable? the install i have is only around £400, so i dont see much point in buying top end cable, but a well shielded cable is a must - right now i'm getting general hiss, and alternative noise running the RCA through the center console.

 

https://www.s2ki.com/s2000/topic/853...t__p__20400634

 

i've gone and bought some higher end ones - £23 delivered, for Connection BEST Series 2 Channel RCA 2.5m, from CarAudioDirect.

 

That was quick, I didn't get the chance to offer you a set I had that don't get used any more, maybe I should stick one the multi changers I've got in the boot myself? Although those cables will be too long too.