Normally in audio stuff you calibrate stuff at 0db at 1khz, done tons of real tapes / cassette tapes cd players, dat tapes and other types
Unless it is specified at other frequencies, you have pink noise and white noise generators too
A scope will be very good at 1x, you don't play with dangerous levels, at 10x or 100x is good to get higher impedances on the probe if 1x create some signal load .... on too sensitive circuits like head amplifiers
The best would be a scope with an integrated signal generator, 2 in 1 instrument, It would be the best for trouble shooting
For me "an old era tech" i would use an scope before a meter, or dual input meter ....
But portability wise a good meter would do fine, i really don't know the Prova brand, maybe they are good at 60k counts on each display / channel
Every one here can argue over this and that, it really depend on the OP need(s) and portability wise