Hi,
Right, some manufacturers moved to a simple "Loudness" circuit that if engaged, applied a fixed amount of bass boost and (sometimes) treble boost as well. Pioneer has always done that (my in-dash Pioneer preamp/controller in my car does the same thing). The treble boost really isn't necessary.
The fixed "Loudness" switch is, in my judgment, less successful than the old variable loudness control. You may find if you switch in the "loudness", it will apply too much bass boost and lower sounds may get "plump" or "fullish", especially male vocals or dialog. It's quite unnatural. But there may be one volume setting where the "Loudness" switch sounds good. In some respects, just manually using the bass control to apply some boost works better.
Regards,
