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. 
How much power?

NAD has a lovely set of mini integrated amps I really like in that price range. The 3020D is one of them, but I think they have 2-3 models.
I've had the Musical Fidelity Nu Vista M3, which was highly regarded back in the day.   I found it to be more bling with little musical substance.  In that price range, I agree with NAD, or finding a rebuilt vintage Marantz or Sansui.
NAD = not always reliable
I would like to have a full size unit to fit in a rack. Power wise I want 50w or higher. I would like phono input and sub output capabilities.
I am not too familiar with creek stuff. 
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.
I like Cambridge as well, I've owned the CXA80, but it does not include a phono input.
I dislike Musical Fidelity and find their stuff hardly sounds warm.  Cambridge is better but again, not warm. Try Marantz.
Creek is coming out with newer higher end gear.  They will unveil it at the Bristol Audio show coming up this week

Musical Fidelity jumped the shark years ago.

With the new Creek releases that will depress the prices of their previous generation integrateds, making them fall within your budget.

My NAD 7020 has been acting up so I decided to retire it. I settled on the Marantz PM6006, but after about a solid week of burn in it still sounded horrible to me and I returned it.  I just ordered a Cambridge Audio Topaz SR 20 and hope it sounds more to my liking. If that doesn’t work, I might try Creek or just get my NAD serviced. 
There is a used Yahama A-S501 for sale here on AG. Has Phono and digital inputs as well as sub out.
Just set up my Cambridge Audio Topaz SR20.  Sounds just like my old NAD 7020.  Paid $425 for a refurb on the CA website.