In some cases, upsampling will improve the output of your D/A converter. The low-pass filters incorporated into the upsampling process will essentially replace the filters in your D/A converter. If the upsampling software has better filters than those built into the D/A, then you may see an improvement.
We would not recommend spending extra money to get the 192 kHz version if a 96 kHz version is available.
Our DAC2 D/A converter will provide exactly the same performance at either 96 kHz of 192 kHz. However, in most cases, many A/D converters (used to record the music in the studio) achieve better performance at 96 kHz than they do at 192 kHz. But, these differences will be very small.