As I'm switching over from a HE1000SE-focused audio setup to a Susvara-based setup, I'm moving components around in my audio rack.
I'm temporarily using the InPol as a preamp, and it does that job better (to my ears) than the iCan Pro I was using previously. It's interesting because the iCan Pro uses a motorized carbon-based potentiometer to regulate volume in the analog domain, while the InPol uses a pair of Burr-Brown PGA3210 chips to control the volume digitally.
Strange to think that a digital volume control "sounds" better than an analog volume control, but the InPol's volume control is much more linear and has more granular steps compared to the iCan's volume control. The InPol probably has a better analog output section than the iCan, as well.
I thought the iCan Pro, especially in solid-state mode, was a very clean-sounding preamp, but I find the InPol to sound cleaner. Even with tubes in the InPol's signal chain, I can hear more nuances and subtleties in the music than I could with the iCan Pro.
Once I get a proper preamp with two XLR outs, I'll be able to switch between the InPol headphone amp and my new amp setup.