Upgrading Integrated Amplifier - Musical Fidelity?

Hey guys, I need some input as I have an old trusty onkyo 9555 integrated but want step up in sound quality. I am looking at the Musical Fidelity m2si but do not know much about the Musical Fidelity line or sound signature. I like a warmer sounding amp and not too clinical. Looking for some suggestions in the $400-$600 range.