I’ve never owned or sampled a Rhodes, but I have done a couple of samples for the PX. Here are my thoughts. (And I’m assuming your Rhodes is mono and without MIDI unless you have one of the brand new ones)
— Mono is fine if not preferred. The typical effects you would add to a Rhodes will add that stereo vibe.
— Don’t record through anything but a good board or AD/DA interface. Don’t record through EQs, Compressors, or any other effects. If you wanted to create loop points in your samples, a compressor (depending on settings) could make that more difficult. Just get clean samples, you will normalise the sample files later.
— Velocity Layers and Round Robins… I would personally do something like 4 velocity layers with several round robins per layer (as many as your target file size will allow). Since you’re playing an instrument that is not MIDI enabled, you’ll be striking the keys yourself. This means that there will inherently be some natural variation between each strike even within a velocity layer. Once you add round robins on top of that, you will end up with an amazingly expressive instrument.
— Tend towards longer samples with natural decay rather than trying to do shorter looped samples.
— As I said, earlier, normalize your samples.
— Even though your sampling process can’t be automated (since you’re using a rhodes that, presumably, does not have MIDI), still consider using good quality sampling software. It will offer other features that will save you a lot of time and effort: batch normalizing your samples, automatically mapping your samples across the keyboard, organizing your velocity layers and round robins, etc.
— Before you start, just do one sample of a key in the lower register of your keyboard, with a high velocity, and a long sustain. Then analyze that file for a couple of things. 1) the quality of your signal chain, and therefore, the quality of the sound sample you are producing. You don’t want to do 600 samples to get to the end and then find a problem. 2) Once you have that sample recorded, what is the file size you’ve produced? Use that information to plan how many velocity layers/round robins/keys-per-octave you want to sample based on how much space you’re willing to dedicate to the sample instrument.
Hope this helps