I have used poly caps in all my components and replaced the electrolytic whenever possible(space limitation, values of cap, cost etc.) Not all poly caps are the same. Some may be good for bypass and not good for coupling. One has to try until having the desired sound.
I replaced with poly caps in my speakers' crossovers, the speakers are more quiet and clearer sound with deeper bass.
I replaced them in my cd player and the sound of the cd player become smoother. Some cases it changes the character of the sound for the better.
For the preamp, I actually replaced the electrolytic in power supply one by one and compare the difference each time. Each replacement made the music smoother and sweeter. Yes, in the power supply. I did that until no more electrolytic.
you can try that with inductors (for speakers) and resistors (for all).