4 ohm amp into 8 ohm speaker or 8 ohm am into 4 oh

That is the question? I have had so much different advice on this matter my head is spinning. Here is the scenario. I have a Linn Classik Musik that runs 4 ohms at 75w. Should I match the ohms for it to get the best sound and attach it to my Legacy Monitors that are 4 ohm impedence (25w to 300w) or should I attach it to my Monitor Audios that are 8 ohm impedence (100w). The Linn tech told me I would get better sound from the 8 ohm speaker rather than the 4 ohm Legacy. I thought we should match ohms?

I have another system that is an MD208 which is 8 ohms at 100w and 160w at 4ohm. Which speaker would be best for this, which is my nice home system by the by.

I want the best and safest match for these components, as they will be with me for at least 10 years.

So which pair do you all suggest for best sound and safest long lasting running. Should I match my ohms?

Thanks

JM