Are machines pinned to hardware regardless of volumes?

The machines api blog post says:

machines are pinned to specific hardware in our datacenters

I am wondering if this is only for machines with volumes, or if this is all instances regardless of whether a volume is attached

As of now, all Machines remain pinned (or at least assigned Public IPv6 address don’t change across restarts: Leftover DNS Records - #4 by kurt).

Thank you @ignoramous !