I agree with Tireguy, but will add another aspect to induce head scratching and possible frustration (what would the audio hobby be without it?). I don't know if the Melos is a truly balanced design, nor did you mention if your source components are a balanced design, or if you suffer with noise that may be attributed to your present interconnects, but these are all issues that should be thought about prior to making any decision.
I would trust that your present amplifier was selected based upon compatibility with your listening tastes and speaker selection. Indeed, your pre-amp upgrade was probably selected with these, and other desires in mind. If you enjoy the sound of your system, IMHO changing amplifiers to match cable types is the tail wagging the dog. Pick the components you like, and then interconnects and speaker cables that enhance the qualities in the sound that guided the purchase of your components. Happy listening!
My opinion, for what it’s worth.