Asynchronous USB input 24/96 vs 24/192

192khz music takes up twice the disk space of 96khz music and is still relatively uncommon. That said, don't worry about 192khz, just worry about how good the DAC is at 96khz and how well does it meet your system needs.

In a "modest" system I doubt that it will be revealing or transparent enough to detect the minor subtleties of the sampling differences.

I also have read that not all music benefits from the larger bit rate increases. Many claim to achieve superior results with well produced Redbook Cd's.

The most important factor in my opinion is how the original signal was mastered. The quality of the original and having a low noise floor and absence of distortions to the signal are paramount. as always YMMV, in your room with your equipment and musical tastes.