The 3rd generation of this preamp finally arrived after much wait, as the eBay seller Q/A the unit for me, making sure it has no hum, pristine cosmetics, etc, before shipping out to me.
This isn't any formal review nor I am affiliated with Sheer Audio. The preamp is very sensitive to isolation and power cord. Dead quiet, hum free, very smooth and intimate, less tubey-sounding than I expect. It's hard to find something less than $2k in used market to sound like this.
We shall see how it sounds after a few more weeks of listening.