lookin for a bit of advice please. i have an active sub which came with the tannoy fx5.1 package. it is connected to my amp with single phono rca cable and into the sub left analogue input. the thing is i'm needing an 8m length of phono cable. tvcables.co.uk. does a digital coaxial cable in this length, could i just use that? would there be any difference in sound between a good quality phono cable or just an el cheapo? any info would be great .