How does my laptop’s processing power improve sound quality?

The processor built into your Mac or PC is powerful enough to run video games and edit 4K video… but also replicate some of the most sonically intricate instruments, like the piano.

A laptop’s available processing power unlocks the exciting world of modelling, where rather than using lots and lots of individual samples for each note and each velocity for a piano, software models each of those possible variations. This provides an instrument that is super light when it comes to RAM use, but you get a little more of a DSP hit because rather than just playing back a sample, the computer has the calculate in real time what the sound of the piano should be for each note and each velocity that you play. Though some hardware keyboards have embraced modelling techniques — Roland have had pianos for quite a while now that use "Supernatural" technology which is a combination of sampled sounds and modelling tech — computers offer far more power out of the box. In laptop land, the best-known modelled piano is Pianoteq, which I use a lot and love, and which has a tiny RAM footprint. 

The amount of DSP available in a hardware keyboard, or on a computer, will determine how many things it can do at once, and how quickly it can do them. For example, running complex reverb algorithms or calculating notes played on a modelled piano takes quite a lot of DSP. Even a really basic laptop should have considerably more DSP available than a hardware keyboard, and this translates to being able to use more complex FX, and run more sounds and processes at the same time. This doesn't necessarily mean that the computer option is going to be immediately better than the hardware option, but it does mean that there are more FX options available.