I used PianoOne (free vst), Vocaloid 2 Prima (it's the only solution I found since unfortunately I cannot afford to pay for a real mezzo-soprano or soprano; I found the software at a very low price and bought it a few days ago), the voice is so-so, it is still synthetic, and the available phonetics are in English and Spanish, anyway without killing myself too much I "managed" to do something. I recorded the piano first, then transposed it by a minor 3rd, that's why the sound is muffled; even the tempo is intentional, anything faster would have been a problem for "the vocal performance," so this is a middle ground; I intend to improve the piano part, I have identified some points where I can embellish it without changing the structure:
Very delicate and at times quite heartfelt... the piano module seems excessively repetitive to me and I struggled a bit to get through the 5 minutes and change of Lied.
In general, I didn't hear anything excessively strange.