This is an interesting one. I first did not like the 660S stock. I found it to be basically a brighter 600 with slightly more resolution in the treble. I did see that detail did increase in the highs, but.. why? Why would anyone use this over stock 600?
Then a friend asked me to try making this, based on the OG design. I did, and- I was honestly surprised by the results. I know it sounds like a cop-out, but this sounds like the lovechild of a 600 and 650.
It’s currently gaining good popularity because of its high efficiency, which makes it more friendly for portable and gaming use.
I very much like this one- it’s my go-to when I’m not using my JAR800.
Impressions here.
Price: 600 USD
Headphone not included. See here.