All other things being equal, there is no good reason to not try "mixing and matching" audio components.
Things to consider though.
A vacuum tube preamp has more limited drive current and a higher output impedance than a similar hybird or solid state preamp. Thus you should be aware of the input impedance of the power amplifier and the distributed cable capacitance of the interconnects, and make sure you are not creating a difficult load for the preamp to drive.
Also, be aware of differing sensitivites of different brands, there is no good industry standard that is followed. If you have an amplifier that has a high input sensitivity, then you will loose useful range of your preamp volume control and have a poorer signal to noise ratio.
Also be aware that all other things being equal, louder sounds better. So if you substitute a new component that has a bit higher gain, it will tend to "sound better" at first listen, even if it really is not better.
Finally be really careful in selecting an amp and or preamp for a high sensitivity horn loaded loudspeaker. The speaker causes the system to have a much poorer signal to noise ratio, you need to select really quiet components ahead of it or the noise level will disturb you.
Otherwise, have fun. Nobody has got it perfect so far.
Frank Van Alstine