I underestimated the size and power of this NAS. It is rather larger, but not so huge after all the packaging was removed. The fans are somewhat loud since it defaults to medium speed when there is a PCIe card installed. Full speed is quite loud and not what I would need anyway. I may try to find quieter fans later on.
Read speeds are much slower than writes for some reason. The Xenon CPU has minimal utilization, so I don't know if there is some bottleneck in the X520-DA2s or what.
According to the Synology DSM the Party check (that will take practically forever...) may degrade performance, but why the reads rather than writes?
Sequential Read : 480.264 MB/s
Sequential Write : 865.305 MB/s
Random Read 512KB : 452.122 MB/s
Random Write 512KB : 727.911 MB/s
Random Read 4KB (QD=1) : 20.494 MB/s [ 5003.3 IOPS]
Random Write 4KB (QD=1) : 20.187 MB/s [ 4928.4 IOPS]
Random Read 4KB (QD=32) : 94.252 MB/s [ 23010.8 IOPS]
Random Write 4KB (QD=32) : 55.338 MB/s [ 13510.3 IOPS]
Test : 1000 MB [E: 0.0% (0.2/46362.1 GB)] (x5)