I have a Sony HAP-Z1ES. It comes with a 1TB HDD from factory. It wasn't long before I had that filled and had to replace it with a 2TB HDD. Later on, I read somewhere that replacing the HDD with an SSD would improve the sound quality. Of course I had to try it. I found a 2TB Micron SSD for cheap on Ebay. Expecting a minor improvement in sound quality, if any, I fired it up and was immediately blown away. Not a minor improvement, but a large one. I was up half the night listening to all the songs I was familiar with to hear the difference it made. Fast forward to adding an external DAC, again being blown away, way more than the SSD blown away. This was a new level of blown away. A little while after that I started thinking 'if a DAC made that much difference, how much would a front end make?'. Get rid of the Sony and get a higher end server. After a lot of looking, I found a good deal on a demo N100H. An item I had seen in my local HiFi shop of choice but never thought I would ever be able to afford. Before even paying for the unit, the gears in my head were upgrading the HDD to an SSD. It made a huge difference in the Sony so I had to try it in the Aurender. I then started reading the forums and learned how the Aurenders cache the data to an SSD prior to serving. That did not deter me. If bits can be disturbed traveling from an HDD to the electronics then bits can be disturbed traveling from an HDD to the cache SSD. I will make this upgrade. Oh yes. After finding the SSDs I wanted, paying lots of money for them, and pulling my hair out for days trying to get them to work in my N100H, I fired it up and listened. Does it sound better? The delay in swapping everything out and the headaches trying to get it to work had muddled my memory of the HDD sound so I could not say for sure one way or the other, although I think it did, but not as much as with the Sony. Regardless if it did or not, I hate mechanical HDDs and would have done the swap even if I knew it would make no difference in sound quality. I get peace knowing that I have good quality SSDs in there shuffling my bits around and serving them up to my DAC. I'm loving the sound of this thing.
If interested, here are some photos of it after the upgrade. As the photos show, I used Samsung 860 EVO drives. 500GB for the cache, 4TB for the storage. 500GB is overkill for the cache but it was all I could find in an 860 EVO. I used a Silverstone thin double right angle SATA cable and created my own SATA power harness from an old ATX power supply. The harness is inside a channel I designed and 3D printed to keep it away from the other electronics. I could have used the harness that was already in there for the HDD but I didn't like it sitting so close to the USB circuitry. I'm no engineer but that just didn't look like a good idea to me. I also used double sided tape to keep the SATA data cable away from the board and against the outer casing.https://juniorbarnes.smugmug.com/Aurender-N100H-SSD-Upgrade/