that to use for transcoding is only supported with 918+ and that needs at least a 4th gen intel cpu
from these only the i7 is 4th gen (1st number is the gen)
beside the "no sata port multipliers with xpenology/dsm" you should do some number crunching
your delock 89384 has 10 ports, is a 2 lane pcie 2.0 card
thats 1000MB/s for 10 disks
if you are aiming for transcoding and going with 918+ the lsi sas might not be the best choice, you might want to read this
https://xpenology.com/forum/topic/28321-driver-extension-jun-103b104b-for-dsm623-for-918-3615xs-3617xs/
i'd suggest one or two jmb585, pcie 3.0, two lanes, 5 ports, thats ~1800-2000MB/s for 5 disks, good enough for hdd's
if you systemboard has two wider (then one) pcie lane slots you can have 10 ports or 5 ports plus 10G nic
the 1x slots could also be used with cheap pcie 1x 2port controllers (there is a jmb582, same as before but only 2ports
https://www.sybausa.com/index.php?route=product/product&product_id=1043
if you start with 8 disks and 6+5 ports you can still have a 10g nic and with two pcie 1x slots there are 2 x 2 more ports if you need it
atm all cheaper 8 or 10 port ahci controllers (without multiplexer) that use 2 x pcie2sata chips and a pcie bridge chip use ony pcie 2.0 two lane to the hos computer so its nor really a good choice but maybe in 2021 there will be at least a cheap pcie 3.0 bridge chip that would make 2 x jmb585 cards a possible choice
(asm1166 is 6port ahci, also pcie 3.0 but my test card had weird problems and the computer saw 32 ahci ports, so if going with this there might be unpleasant problems as dsm is only ok up to 24ports in the state we have it now)
usually it should do, i have a 400-450W with 12 x 4TB disks