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. 
apstoltz
I tried to downsize my system by selling my Pass Labs X250 but found that to be a terrible mistake.  Over time and plenty of gear I finally realized what I wanted was the Pass sound, so I finally got a Pass Labs X250.8 to get back to happiness.  But along the way I had purchased a Musical Fidelity M6si to try out.  This was so not what I was looking for that I sold it very soon after getting it.  It wasn't warm, didn't grab my attention, didn't have any intestinal fortitude.  Instead of a lion's roar I got a cat's meow.  I liked the warmth of my vintage Marantz 2252 receiver more than the MF.  
Check out the Marantz PM7005.   Just a bit over your budget, but you can find them used for less.

There's also a used PM6006 on here, for under you budget.
Will the marantz be a step up in sound quality? Someone told me I should look at the new Cambridge Audio offerings.