Really? Appears to be quite a sweeping statement!the tone controls or eq or DSP is to correct the sound reaching at the listening spot. Most tone controls are set at frequencies that are mostly problematic to most rooms. I would say pure line amps sound only good in an acoustic chamber
I would like to know the EQ frequencies chosen by various manufacturers like Denon, MArantz, NAD, Bose (*gasp*) etc.
The problematic frequencies in most room is due to standing waves and comb filter effect due to room dimensions (typically between 10 feet and 20 feet).
You are simply referring to most people's preference to boosted bass response (frequency lower than 80-100 Hz) vs flat frequency response.For example, the Ifi Zen DAC has a one click bass boost function which is simply superb and works wonders in my room. There is a massive difference in the bass response with it switched on Vs switched off. And it accomplishes this with minimal to no intrusion on the mids depending on the speaker i.e. you can hear it in some while totally inaudible in others.
The RME ADI-2 DAC has a 7 band PEQ (advertised as 5 band but effectively 7 via the lastest firmware update) through which you can define Q values, frequency, peak etc. To get a similarly gratifying response to the ifi zen DAC's bass boost, i had to perform a number of REW measurements and tweaks on the PEQ to get it right. And i would imagine that this process would be daunting to many as it not only involves a lot of effort but also an understanding of the basics, not to mention a certain level of comfort with computers (for measurements etc).
This is not room / equipment correction.