NAD C270

Hello everyone. I have a dilema which I am hoping someone here can help me with. I have been listening through my mid-fi system for the past several years and have been happy with it. My system consists of a NAD c340 integrated amp, NAD c520 CD player and a pair of B&W 601 speakers. Recently I decided to upgrade my system but not neceseraly change everything. I went to several shops in my area and everyone has given me different opinions. One said to change my speakers, the other to change my inter connects while the third told me to add the c270 power amp. Basically, all I want is to improve the sound that I hear without breaking the bank. So what do you people think I should do? Thanks.