where is ref level on the realitine scale

ok relative, third time is a charm. is 0dB ref or max? or is there no set number. the reciever is thx.

If you're talking about digital level, ref is full-scale -- i.e. the highest. Anthing else will be termed in negative (as in "-3db" etc). Accordingly, the lowest scale on, say, 16 bit should be s/where around -96db.
Sorry if I misunderstood yr question

For magnetic tape it is 0 VU referenced at 250nWb/m (nanowebers per meter) input
For phono cartdrige output (mV) it is at some reference velocity in cm/s (the actual number escapes me)
For speaker output (dBspl @ 1M) it is at 1mW/8ohms reference input
I hope this helps.