… does use the same code as PEQ gain, headroom, or DSP volume.
I’ve just reassured that my setup doesn’t audibly exhibit any frequency response tayloring on switching headroom 0dB on/off - no volume leveling, PEQ, or DSP volume adjustments were enabled during that test.
Anyone convinced in that happening could easily setup a loopback of Roon’s stream to verify with appropriate free measurement software… or just use their USB mic to measure acoustically…