I'm just wondering if others are having to do the same and if I'd have the same issue with a real stack?
Yes, you have to adjust, whether it is a “real” rig or modeled. The issue is that our brain doesn’t perceive frequencies the same at low volume as it does at high volume. That’s exactly what
Fletcher and Munson studied, what their experiments proved, and why it’s important to understand it.
With an amplifier with knobs, we’d twiddle them and adjust them until they sounded how we liked. We might move the cabinet to a better position also. When in a room where we turn it up we’d adjust again. Eventually, we know our rig sounds great at stage volume and get tired of constantly adjusting for bedroom volume, and leave it alone. If FOH gets a signal then they’re responsible for EQing it.
The modeler has no way of knowing where it’s being used, so you get to adjust it for the room, but doing so can be frustrating because it’s so much more flexible than the amp, and with multiple places available to adjust EQ it can be daunting… adjust the amp tone? Adjust the cab? Adjust the FRFRs? What about the FOH send?
I initially adjust my basic In->Amp->Cab->Out preset EQ with headphones using a compensating GEQ or PEQ block just ahead of the Out block at 90-ish dB, then remove the block and save the preset, then begin adding effects. If I ever want to adjust the EQ again, I can reinsert then remove the block after adjusting, or I can translate a minor change in my head, and save it again. My FRFR cabs are set to be neutral, so I know that the modeler will output the signal I told it to, the cabs will do their thing, and I just need to have the volume at 90-ish dB and it’ll sound good.
Some rooms sound different than others, as do positions in the room. I can easily scoop my FRFR cabs or flatten them with a quick change to their amp, or I can adjust their positions. The other night I was on a different spot on a stage than I used before and was getting too many lows. Using the global EQ in the modeler I rolled off the lows until they were in the ballpark, then finished the first set and thought about it as I played. I realized that the FRFR was the smarter place to adjust, changed the switch to scoop it, reset the global curve, and the overall rig sounded great the rest of the night.
This is experience, some of it is studying, then combining the two.