As above. Buy a drive that matches the speed of the data drive and the interface.
e.g. I have a 7200 rpm HDD on my server. I backup with a 7200RPM bare drive using a SATA hot swap bay. I could use eSATA as well.
NVME I am currently using a SATA SSD through an eSATA dock but I could probably...
I went through about ten pairs before I found some that I liked enough to keep. I suggest you buy used on one of the headphone sites and resell the ones you don't like to save money.
The Panaflo L1a was once my standard 80mm, but now I have gone with Nexus. I don't know about the Scythe, but I haven't been impressed by their 120mm fans.
Like someone above said, just send the digital signal straight out to the receiver and let it do the processing. The SR4002 is a nice piece of kit that will do a great job with the digital signal.
I kind of gave up trying to find one, as there is no Canadian distributor, but as of a few months ago they were still shipping in the US with the old riser card.
The riser card is for PCIe16x, so I would assume it fits in the second slot from the top...
Look around. The smallest case that takes a full ATX board I am aware of is the Silverstone LC-04. I believe Silverstone also makes a PCIe16x riser for it.
My Lian Li PC-B25B has washable filters that are relatively easy to access. I made the task even easier by cutting to fit some Demcifilters from performance PC's:
http://www.performance-pcs.com/catalog/index.php?main_page=index&cPath=36_463_500