Yes, it's disappointing M-Audio omitted a dB VU scale. While not fatal, most find dB marked VU scale is at least helpful to gage needed headroom for avoiding clipping, and adjusting for adequate recording levels. For me, not having a marked dB scale while recording is like "driving with one eye closed"
So here's one 'no-cost' solution:
Practical adhesive label showing the missing dB scale markings is FREE if lucky and/or having courage for accepting challenges requiring hand-eye-brain coordination.
If lucky to have Brother 300dpi USB connected TZ label printer, and want to print this label yourself and for others, then HERE
www.sonicstudios.com/mt2496rv.htm#tip2 is posted the design file for download, compliments of Sonic Studios. Or design your own, maybe share the experience.
For those not so lucky with having the printer, but in US or Canada, and still wanting the challenge of applying a much needed very tiny label, get the FREE 3-line printed label (3 tries getting it right) by sending #10 or smaller self-addressed -postage paid envelope, to: Sonic Studios, DB LABEL OFFER, 1311 Sunny CT., Sutherlin, OR 97479 (USA)
NOTE: Label requests without pre-addressed envelope and/or full 1st Class postage get Q-guy-vaporized!