Thanks for the replies. The MIDI keyboard is only for playing a virtual instrument with your fingers and through a PC-based sound system. I am talking about PCM digital audio at 44.1kHz / 24bit which I upsample on the fly to 176.4kHz (with a better resampler than the one integrated in the virtual instrument which generates a lot of aliasing) in order to be able to treat it with hardware / software DSP (for example passing simply the sound through the Pulteq EQP-1A is truly spectacular and of many implementations that of Universal Audio is the best).
It is true that oversampling does not bring an improvement in itself but using a DSP at a higher frequency can lead to a better and smoother result (many DSPs work internally with oversampling). Basically you can only process audio in PCM, with DSD you can do very little in real time.
Some DACs also work in upsampling, for example Crane Song professional audio products always upsample to 211kHz and use proprietary reconstruction filters for accurate time domain response. The dCS products also use DSP for upsampling (PCM-> PCM or PCM-> DSD as in the Scarlatti DAC or in other more recent models, perhaps Rossini).
More generally it depends on the context. How to say PCM generates sound differently than DSD but this also depends on the hardware implementation. You may like PCM or DSD more. It also depends on the type of digital conversion that is done and for this reason I mentioned HQPlayer which is very flexible in this.
Ultimately all this digital sound processing involves latency and the various delays are additive to the point that if you listen to a CD it makes no difference but if you have to play a musical instrument it can be impossible. From when you press a key to when you hear the sound it is best not to exceed 50ms.
I would hate to buy a dCS product and then not be able to use it for this low latency purpose …
Best Regards,