can u cut longer interconnects and reterminate?

No issue at all.

Unless you have a very odd/exotic cable design that may pose problems if you cut it, you should have no problem at all. Sound quality will only be effected if you don't do a good job. If its expensive, factory terminated cable, it would probably be a good idea to send them back and pay to have it professionally.

If you end up doing it yourself, measure everything out first to see how much you will definitely need. Hopefully, you'll have a little left over. Practise on that first so you don't end up with 10 meters of weed wacker cable.

If it is a cable that you went to great lengths to match to your system then I'd recommend that you let the company do it. Both for the reason mentioned by Elizabeth as well as the fact that you will get a matching RCA, solder and terminating technique of the original cable, all of which can effect the sound of the cable.

If it is less critical cable it should be no problem, although some IC's use varnished wire strands so you will have to use a higher heat to burn off the varnish first so it will then accept the solder.