If your VCV bank has inconsistent volume between vowels (e.g., "i" is loud, "u" is quiet), Wavtool4vcv will preserve that inconsistency. Run your final exported vocal through a compressor (like ReaComp or LoudMax) after rendering, not before.
OpenUTAU, the modern successor to UTAU, uses a different rendering architecture (Worldline-R) and does not rely on external resamplers or wavtools. However, thousands of users remain on for three reasons: wavtool4vcv
(Adjust sample_fmt to s16 for 16-bit or s32 for 24-bit-capable containers; use sox for precise 24-bit output if needed.) If your VCV bank has inconsistent volume between vowels (e