Anyone have any experience with these? Picked one up for cheap to drive an old pair of Klipsch, which should be easy to drive. It’s a Fosi Audio brand and touts 50X2. Also has a headphone jack. The headphone out does a pretty good job with my HD 650’s, but that’s not really what I bought if for. The amp itself is absolutely lifeless sounding with the Klipsch. I’m fairly certain the Klipsch aren’t to blame as I tested them with old Yamaha receiver that I believe is also 50X2. My question is are all Class D amps this wimpy?