It's not the same, but we have a bunch of r650s as work and they are loud as hell. I don't know if they're all like that or if it's just their specific configuration, but the fans are pretty damn loud. We also still have an r620 in the Room. That one isn't ass bad, but still annoying.

We have a bunch of r730s and r740s, those are pretty chill.

The 600 series are all 1U, they will be obnoxious if the fans are spun up high.

That said, if you’re not going to be hitting the CPUs very hard, you can use iDRAC/ipmitool to control the fans and bring them down to 10-15%. At that level, they will be an audible hum, not super loud.

I would recommend a R700 series since it’s 2U, more heatsink, larger fans, you can get away with turning the fans down more.

What else are you running on the server? Most would suggest not running certain other things on your pfsense unit, and some don't even thing running it as a VM is a good idea. Seems to be a big debate though so it's not necessarily cut and dry, but if you run a bunch of VMs alongside it just make sure you know how to keep everything stratified and protected.