Most poor audio quality comes down to engineers not taking into consideration the ESR and capacitance value of the caps, not at 0v, but at the operating voltage and maximum temperature they will be operating at. In the case of input DC filtering, the second problem occasionally is the caps leakage current at the operating voltage and temperature. On occasion, some of these so called Audio Grade caps may have a slight improvement on these extended operating metrics, but, a properly engineered amp designed with normal caps taking in all the extents and designed to operate outside, or better than it's audio specs should operate sounding perfectly excellent. You shouldn't have to be wasting your time on these Nichicon cons.
The only 2 case where some so called audio grade cap may be of use is either in small values where you want to create a filter to alter the sound which is not the case with the caps listed above. #2, inside the speaker crossover, where you want to filter full power, like 250 watts in series through the cap, driving that low impedance audio signals to a specific speaker driver. Again, the caps above are useless in this circumstance in that really high end speakers use much larger, higher voltage, extremely high performance consistent esr over dynamically driven operating loads. Again, nothing like the above Nichicon, or anything you can even purchase at digikey. (Note that such quality caps do not advertise some BS on some electronics parts supplier flyer, their reputation is earned and they are known in the industry and they don't need to advertise in such ways...)