I've used my Concero in lot of systems and it really doesn't differ that much in sound quality. For me that is quite an endearing quality compared to some other more finicky DACs I've used in the past. I'm sure other people will hear more differences than I do, but I'd really say it is close to splitting hairs. The protection I've seen on the Concero is more geared towards voltage drops and inadequate current delivery.
My Concero has been connected to following devices:
- Powered USB hub on my Dell monitor
- Core i7 PC with Seasonic Platinum PSU which has extremely low ripple
- Macbook Air/Retina Pro (adapter and battery powered)
- Apple USB power adapter
If you do the math, spending from $100-200 extra on your Concero is adding another 16-33% on top of the original purchase price. For that kind of money you could purchase the HD. With a filtered supply you could expect a performance gain from anything between 0-5%. It only makes sense if your current system is feeding it garbage power and you are not getting anywhere close 100% of its performance which implies that your money might have been better spent on a DAC not dependent on the quality of the USB power.