The Amplitude Scaling is not a parameter set available for user manipulation. However, you have several options to adjust your overall output balance within the CP4 Stage. Depending on the VOICE you have selected it may already come with built-in Pre-Amp. The Pre Amplifier on the acoustic piano models are very much like adjusting the characteristics of microphone pre-amp used to amplify the piano. In the Rd (Rhodes) models the pre-amp is clearly understood as a physical device that was a part of that instrument. When you look at the parameters of Pre-Amp on the Acoustic Piano Voices you will notice the parameters are very much an EQ.

These musical EQ's are at the heart of the physical modeling going on in the CP4 Stage... Try working with these to balance your sound. And recognize that the problem you are describing is mainly making up for frequencies not being heard in a specific environment with a specific set of speakers. You are very subjectively creating an EQ balance to compensate for frequencies either being masked or are deficient in the sound system.

If you can make sure you are in front of the sound system when making decisions about high frequencies (you cannot determine high frequency content if you are off-axis) I only mention this because it is the most common mistake in setting EQ. High frequencies are most directional of all.

In addition to the physical modeling EQ's built-into the piano models, you have the VCM EQ 501 as an insert. With these boutique level EQ's you should more than be able to compensate for most any situation.

As a reference the acoustic piano is "A" 27.5Hz ~ "C" 4,186.01Hz.

Thank you bad mister for your indepth. Really apreciated!
Problem is mainly with CFX samples.
Now, I came to the parameters manual after many try with eq-ing both with amps and eq501, and with cutoff and resonance also, non the less trying different piano voices and customizing velocity curves (I'm sticking mainly with cfx standard and cfx-fl for purity sake here), where the fl maybe is slightly better in this regard (maybe-and-very-slightly).
By the way, is it only different in that it has a different tuning?

I came to a better situation, I'm almost there, but not THERE actually.
Also soloing jazz in trio or duo, comping with the left hand is too intrusive.

The CF and S6 suffer less of this problem. Maybe not at all indeed.
(The CF in the CP5 was badly suffering from this in my opinion and I'm pretty sure it has been corrected in the CP4 fortunately)

Please let me know if you have other suggestions.

best!

To me, your issue is in the reproduction of the piano through a sound system. It is one thing to EQ a piano sound in a keyboard like a CP4 Stage as a standalone, it is quite another to compensate for room acoustics, speaker deficiencies and battling for space in a composite mix with other instruments. The EQ within the synth architecture (physical modeling preamp, and Insertion Effect EQ) can directly affect the piano sound, the EQ on the Output (the 5-band front panel EQ) is designed to adjust and compensate for the room you are in currently... and can help you overcome "masking" (battling for frequency clarity in your sound system also tasked with reproducing other instruments and perhaps vocals).

To make an exaggerated point: a piano alone in the mix does not have to compete with any other sound for its harmonic space. You will EQ it according to what you hear. As soon as you add a bass player, your opinion about the low end will definitely change, as the two start competing for low frequency space. Each item (instrument) you add will compete for some range of the pianos enormous range.

You can blame the piano, or recognize what your ear/brain does when presented with multiple instruments sounding within the same range through the same speaker system. Also that on stage, the player is typically in the worst position to judge what the band sounds like through the house system, particularly if you are not in the best seat in the house (out front of the speakers, equidistant from each side.

Ideal situation: monitor yourself and the band in a personal monitor system; let the front of house soundperson deal with what you sound like out front.
Now while this is not always feasible, at least recognize WHY this is the optimum situation. Then attempt as best you can to create this situation. If you cannot hear yourself (cutting through the band) you need to know if people out front feel the same way. It could be a fault in the way you're monitoring yourself. If out front it sounds fine, but you can't hear as you like... you'll need to fix that.

But it is unlikely without a separate monitoring system, to get yourself happy on stage and the audience happy out front of house. The stage is not where you would sit to hear best... the best seat is some distance from the stage center of house!

May I ask what are the differencies between Pre Mic 2Band-1, Pre Mic 2Band-2 and Mic 2Band-3?
I suspect they are 3 presets of the same effect.
So what I can use to work like you describe actually are these 2 insertions: mic2Band and mic3Band ?

By the way, I have a pair of lightweight monitors (jbl control 2) in front of me placed over the cp4 chassis in a perfect stereo position. Not the best monitors out there, but the only one good for this purpose I think (?). Thanks to their verstile input and the cp4 balanced and unbalanced output I can have separate volumes for me and the PA for the audience 😉

The Pre Amplifiers are part of the Modeling within the CP4 Stage's three acoustic pianos.
Pre Mic 2Band-1 is designed specifically for the characteristics of the Yamaha CFX data
Pre Mic 2Band-2 is designed specifically for the characteristics of the Yamaha CFIIIS data
Pre Mic 2Band-3 is designed specifically for the characteristics of the Yamaha S6 data

Each of the acoustic pianos also feature a 3Band EQ version of the microphone preamp. These are all extremely "musical EQs" and have a distinct sound of their own. They are a component in the SCM (Spectrum Component Modeling) engine that is used to recreate the piano and electric piano sounds in the CP4 Stage.

As I mentioned, it's easy to think of the different Rhodes (Rd) data as including the preamp. A major difference between a 1975 Rhodes and a 1978 Rhodes was the preamp was entirely redone. So when cresting the Physical Modeling Spectral data of the various Rhodes, the preamp was naturally included... and the controls over that preamp are provided as variables.

On the three acoustic piano Spectral data, they provide a microphone preamp designed specifically for use with the specific piano, and you are provided variable controls over the frequency balance.