Si te refieres a que los VU no coinciden con los leds, es normal:
"The VU meters on the MB•32, MB•24 and
MB•16 “look” at the same signals as the
console's L/R LED meters. You will notice that
the VU meters and LED meters will not always
agree with each other. THIS IS NORMAL. The
LED meters read peak activity and will show
every dynamic nuance. The VU meters, designed
in the Early Bronze Age, are slower to
respond and therefore show an RMS or average
signal level. This will usually be several dB less
than the peaks shown on the LED meter."
Extraído del manual de montaje del puente de vúmetros:
http://www.mackie.com/pdf/8bmeter.pdf Un saludo.