Mixing speakers and ohm settings

Good evening all,

Apologies in advance probably a really dumb question coming up.  

I have an Onkyo 616 amp and mordaunt short alumni surround speakers.  I'm planning n upgrading the speakers over time and am looking to auction the Dali Zensor 1's to upgrade the surrounds.  First of all the front left and right.  Need to build a new tv unit as the centre speaker won't fit on my current stand.  

The Dali's are 6ohms, where as my Mourdaunts run between 4-8. I've checked my amp settings which is currently at 6ohms.  

Apart from possibly sounding a bit dodgy on my first upgrade I just wanted to check if there is anything else I should be aware of which could cause issues?

im presuming it will be fine. 

Many thanks in advice