However, this does not mean that you can't edit 24-bit, 96kHz files but the converters on your card simply don't convert to 24-bit 96kHz because they're not. However, there may be advantages that you are noticing from editing and monitoring at this level.
For example, a reverb plugin could sound better at a 24-bit, 96kHz level. This is probably where you're noticing the increase in sound quality.