Because flac is the same as a wav, just compressed, so that it is easier to upload/download. Think of a zip file. It's a lossless format, ie, if you convert it back to .WAV it would be identical to the original waveform.
MP3/OGG/AAC/OPUS, by comparison, are all lossy formats, and cannot be restored to their original state. Lossy formats typically cause dynamic range reduction(saturation/compression) of sudden amplitude peaks, high frequency errors(metallic sound, often stemming from quantization errors), and smearing/distortion of tones that are close to one another (ie, chorus effects, or instruments with complex harmonics, also related to quantization). Finally, they simplify stereo content by summing (centering/making mono) all tones above 10khz or so (the cutoff ranges depending on format and bitrate) into the center channel. This isn't very noticeable with speakers, but on headphones it can be a drastic difference.
. . .(Ummm...yeah, way overkill there...↑)
Anyway, if I had a better connection, I would probably use .wav for simplicity, but I don't, so flac it is.
Hi TiamisTiam :) Can I use a 5 second snippet of this sample for a mellow dnb tune? It might get a small scale digital release at some point. Feel free to check out the sort of music I do via https://soundcloud.com/#audiosketch74 Cheers bud, would really appreciate it :) Tom