Hi soderlund,
Let me make a few comments on the Prelude in Em. I got the impression that every note both in the RH and LH were of equal tonal value all the way through until the coda. Actually, they're not! First, the RH is foreground with its bel canto soaring melodic line. It is based on a "sigh motif" much like the effect of a two-note slur where the arm goes into the first note, while the second note is more of a lift-off. You often strike both notes with equal force, destroying the sigh.
The LH is background accompaniment. So you need to balance the hands, and, in particular, quiet down the LH greatly, which is way overbearing and distracting right now. The ONLY important element of voicing in the LH is the variable voicing of the chords--that is, ONLY the top, middle or bottom portion of the chord that has CHANGED harmonically from the preceding chord is brought out for the listener. So, while you are playing a chord with the LH, you will be playing a certain note in that chord more prominently than the other notes in the chord based on the change from the prior chord. The way to play the LH more quietly throughout is to play those chords INSIDE THE KEYS. That is, do not allow the keys to rise up to full rest position once you play a chord. Keep the LH keys slightly depressed after playing. That will shorten the distance between the hammer and the string, meaning the key cannot be energized as much, will accelerate the hammer less, and the effect will be quieter playing in this type of accompaniment.
On the Prelude in Cm, remember that this is a funeral procession receding into the distance. Largo is the slowest tempo in music. I think you need to slow it down even more. Also, the crescendo at toward the end needs to be toned way down to remain within context. By that, I mean that the crescendo might go from pp all the way up to mp at the most. After all, the procession is in the far distantance at that point, so crashing chords just do not fit there.
I've attached my own recordings below. Have a listen, as it might better illustrate what I'm saying here. I think you've brought these pieces along nicely, but there are ways you can apply some more polish to them before playing them in recital.