You will get more complete answers on the computer audiophile site. But to keep it short and simple
1) CA dabblers generally agree that you get best results with an SSD HD for OS because its faster, has no electrical motor noise and is affordable since an OS can be contained on a 64gb drive. Media drive sizes (>500GB) are expensive as SSD, easier to use a standard HD
2) more recent experimentation with SATA OS 2.5" drive shows that you can get further music improvement by using a separate battery or linear power supply to independently power the drive as 2.5" SATA drives only require a 5V DC supply.
Both basically reduce digital artifacts, irritants, fatigue factor
1) CA dabblers generally agree that you get best results with an SSD HD for OS because its faster, has no electrical motor noise and is affordable since an OS can be contained on a 64gb drive. Media drive sizes (>500GB) are expensive as SSD, easier to use a standard HD
2) more recent experimentation with SATA OS 2.5" drive shows that you can get further music improvement by using a separate battery or linear power supply to independently power the drive as 2.5" SATA drives only require a 5V DC supply.
Both basically reduce digital artifacts, irritants, fatigue factor