Hey there 👋.
If you go over to the SPL tab at the top where you move between the different graph types, you’ll be able to see the difference in volume between the different wattages that you enter in the system input power box. 30W (RMS) is what your driver is rated for when under continuous operation (think max volume white noise). If you are happy with the approximate SPL that 1W gets you at 1m distance away on that graph then you can definitely use that figure as a design reference in winISD.
To find out the limits of your current design you can look at these graphs as you increase the wattage to get an estimate of how many watts your system can handle before noticeable distortion.
Just know that turning the volume up beyond this value will then start to give you distortion from either port noise or over-excursion. If you ever hear noticeable distortion (that isn’t port noise), turn it back down a bit to avoid bottoming out your driver and damaging it!
If there’s anything else you want clarification on, please do not hesitate to ask. 👍