I would say this is important decision sonically. I would not be in a hurry. MACs have a very distinctive sound. Make sure that is what you want. MacIntosh is frequently paired with B&W… because Mac is very midrange and bass heavy. Great for rock. Lots of folks love them. But there is more nuanced equipment.
You are talking about moving from ARC sound… granted 20 years old to Mac. Make sure you do extensive auditioning.
Also, putting multiple functions in one box normally means compromised sound quality. All the companies are getting better at it. But if sound quality is your top priority, the you want separates. More advances have been made in pre and amp. If space is a problem then this makes sense… depends on your long term strategy… continue improving sound quality of tidy things up.
Going from older equipment to newer is likely to sound better of course.