Equalizer in a Hi Fi system

EQ alone cannot give perfect natural timbre experience ...Physical acoustics is needed too ...

EQ alone cannot give perfect imaging and spatial soundfield without timbre degradation .. Physical acoustic here is needed too but is unsufficient ...We need BACCH filters crosstalk correction because all stereo system sound unnatural because of crosstalk ...Dr. Choueiri claims and proved experimentally ...

Now between EQ methods be it digital or analog, be it mechanical or electronical , there is differences that are not purely technical but related to the way we may and must use human hearings in audio controls ... Psycho-acoustics studies are not purely grounded in A.I. yet,😁 then human hearings is the object of study and had not be replaced yet even and must have the first and last word governing DSP applications ...

This imply that EQ so useful it can be can never be enough ...

The Fourier linear maps cannot be confused with the human hearing territory so useful they can be as a tool and they are for sure ...The map is not and never will be the territory...

All that above is why your post and experience and opinion could make sense to me ...

My approach to all this would remain digital for room correction (mids down). Digital or analog for bass tone shaping/ bass boost. ANALOG ONLY for treble tone boost.

“The problem with 64 bit floating point is that as the signal gets smaller, the resolution changes, and this creates noise floor modulation. OK so we are talking about over 300dB of innate resolution, but this is subjectively significant noise floor modulation and is audible. Moreover, as a signal disappears into the noise floor, it will be treated differently whether there are larger signals present or not. Now you may argue that these errors are very small but at the end of the day, it's about sound quality, and to me these errors are very significant subjectively. And you only need to look at the Mojo 2 thread to see the very positive comments about the EQ compared to traditional 64b FP EQ.

Additionally, a very important feature is the EQ running at 705/768 or 16FS with all the internal nodes being noise shaped. Without the noise shaping, I would need much more bit depth than 104 bits. This could turn into a significant design problem for me when doing EQ for pro audio. If they process at 192k or greater, I can use noise shaping; but doing EQ completely transparently at 44.1k could be a major headache. Incidently, the benefit of noise shaping the internal truncation errors is that the filter still functions for signals well below the bit depth of the system, as errors are never lost - just re-cycled.”

@mijostyn the above is just released post by Rob Watts himself on Watts Up?… thread on Head Fi  in which he responds directly to my query…and to you most importantly, as I pasted what you said there  

“So Robb. Can I infer here that digital is not all the way there yet when it comes to tonally adding a treble boost, as compared with best studio analog hardware? Specifically talking about treble boost here, the “air band” “

The above is my follow up query to Rob Watts. I will post his response as soon as it becomes available. 

His response is interesting:

”I am afraid I don't know the answer to that for sure - apart from knowing conventional EQ is subjectively flawed. I know a lot of recording engineers prefer analogue desks (using DACs and ADCs with analogue EQ), saying they sound better. How much is down to preferring distortion, or how much is down to digital EQ being poor, I don't know. I suspect it's a mixture of both.

Treble EQ is much easier than bass EQ, as the bi-quad coefficients are large values. The largest problems occur with bass - some of the coefficients are very small. So that small value once truncated and then fed back creates significant errors that then accumulate. With IIR filters, the signal is infinitely fed back (hence IIR meaning infinite impulse response). But if the signal is truncated away to zero, then the IIR is no longer functioning as a filter for that signal.”

If anyone wants to see this it’s at Head Fi.  Thread entitled Watts Up…?