Preparing samples for a piano library

I’m preparing piano samples for a library, and I have these questions:
To manage them properly, I need to make sure they all play at maximum volume, as loud as possible. I have samples with low volume and samples with high volume, all at the same level. The problem is that the bass sounds a bit different when I use WaveLab’s level normalizer, and I’m not sure how to use the maximizer for what I want to achieve. Any suggestions? Thanks.

If it’s just a change in level and there’s no compression, there can’t be any change in sound. Apart from the fact that, as you probably know, the auditory perception of a sound changes with the listening level (see Fletcher–Munson curves).