Yes, I'd say that even with an op amp based preamp circuits, it would be preferable to "treat" every op amp stage through the signal chain as such. Now whether the designer chooses to add small amounts of THD in each stage and/or install soft limiting where the signal could peak out the op amp, having multiple amplification stages contributes to how the sound "blooms" , going from clean to overdriven sound. This is just my thoughts, but so many solid state guitar amps were designed with two distinct channels, it was like a "get out of jail free" card for the designers. The clean channel amplifies with no distinguishable distortion until it hits rail clipping (even for short periods of initial note attack), overloading ungracefully. The Distortion channel is generally one stage with antiparallel diodes hard clipping, and with most this is not a progressively smooth distortion. If you notice that the amp's Gain knob for the Distortion channel is the most touch sensitive part of the amp, it's not gradual edge-of-overdrive increase..it's more like a threshold level for clipping or no-clipping..then likely it's designed like that.