I have always been a huge fan of the Loudness Switch for the reason the OP describes. I find a way to incorporate or replicate in all my systems.
Below are my solutions to add "Loudness" capability to my multiple systems:
- System 1: 70’s Vintage Technics Rig w/Reel-to-Reel with "Tape Loops" (x2) and NO factory Loudness switch, oddly = I run an external Technics Parametric EQ via the tape loop "Set to replicate the Fletcher-Munson curve and correct for my room". When I want this enabled, I flip the switch to monitor Tape 2 where it resides. :-)
- System 2: McIntosh C52 based. I purposely sought out this Pre-Amp because of its EQ, which toggles on/off via front switch. Like above, I replicate the F-M Curve and a hint of Room Correction. I purposely bought this Pre-amp for this explicit purpose and late night listening.
- System 3: Schitt Loki EQ. Just like above, I use this in my Office system with powered monitors to emulate the Loudness curve.
- System 4: Computer - Amarra and/or iTunes. I just do it in Software. iTunes actually has a per-programmed "Loudness" setting.
Call me old school, but give me this (eq) functionality/capability over using e$oteric cables ’for tone control’ any day. If I want brighter, darker, or tighter sound, I turn a few knobs to my liking. If a recording sucks and FLAT isn't cutting it, turn a few knobs. :-)
Bring back the "Tape Loop"!!!!