Did you check on overclock.net owners of ASUS STRIX RAID DLX sometimes had or hear Sound Blaster ZxR.
I doubt that STRIX RAID DLX is worse than ZxR. Probably are very similar, STRIX RAID DLX are newer series and they have time to improve and made card better, did they done that I don't know.
I have SBZ, that level is enough for me but in future when I finish other upgrades and if I have chance I will replace for STRIX SOAR because
motherboard is ASUS, next board will be ASUS and for me is nicer if sound card is from same company as motherboard.
Some people look on 7.1 as advantage, for me is 5.1 enough but I have some impression that ASUS cards give maybe stronger better gaming
experience, but maybe is that only my impression after trying excellent onboard SupremeFX and after several video clips in comparison some
previous ASUS series and Creative.