Don't spend so much money on cable. Basic awg 14 cable will do fine for speaker cable. To get the most from your system you may look into speaker placement and room accoustic first. Many people don't realise that both contribute big factor in sound quality. You may try to adjust the distance between speakers, move away from the wall, toe in etc. If your room is too 'live' or you hear a lot of echo try to solve that by putting drapes, book case, carpet etc on the blank hard surfaces. And if you really want to upgrade the equipment, start with the speaker or probably adding a subwoofer. Your amp is fine.