We use industry standard of 0dBFS = Digital full scale or maximum undistorted signal and we generally have 2v nominal output.
Extra:
What signal level is used as “0(dB)VU” is arbitrary. When we was still working in the recording side, East Germany used -14dBFS as 0VU, other studios used -18dBFS or other values.
Nowadays this usually called LUFS (Loudness units relative to full scale) and is calculated according to EBU recommendation 128. This is a bit more sophisticated than “VU”
Music streaming services like Youtube etc. tend to normalize music to around -15dBFS = 0VU ( -13 dBFS for YouTube, -16 for iTunes and Pandora, -14 for Spotify and TIDAL).
This definition does not really relate to equipment in itself, just to the programme material.
VU stands for “Volume Unit” (though more cynical sound engineers like myself called it “Virtually Useless” even in the 80’s and strictly used PPM [Peak Programme Meter] for recording and mastering) and is a fairly long-term average of signal, so it represents more or less well how “loud” a track sounds.
Many mastering engineers commonly break any 0VU/LUFS rules and (re)master music as loud as possible. So some tracks may actually have -6dBFS as 0VU, before being normalized.
An extreme example, Guns ‘n Roses “Welcome to the Jungle” is -2 LUFS”
