Tone controls -- assuming you're ok with them, when would you try them?

a standing debate whether tone controls are worth the (likely) sound degradation

Which is a silly debate when the mixing console your music was made on has tone controls all over the signal chain. If the circuit is designed well, the tone control won’t ruin your sound by running it flat. Also saying you should at no point need tone controls is like saying I will only ride a bike with no brakes and adjustments because I am that much of a purist that even having the option to stop or enhance the experience to my liking as needed ruins my pure experience. Laughable logic.

microphone selection is the first tone control in the recording chain…….

All the time since there is no perfect room and therefore, even if you are the best set up guy in the world and have added reasonable acoustic treatments, EQ for minor, final fine tuning is icing on the cake. Every LP and CD you own has been EQed many times before it hits your home; no debate like you find among audiophiles in the recording/mixing/mastering industry.

I'm saving for a Manley Massive Passive (I can also use it in my studio) for analog and I do my final EQ for digital using the EQ and room correction algorithms in my Weiss DAC501.

IMHO, the Schitt EQ products are a gift to all audiophiles. The Lokius with six bands is where I would start. I tell everyone who will listen to pick the one in their price range, play with it for a few weeks and return it if it isn't for you. Nothing to lose and a lot to gain.

This will horrify dealers though. In many cases trying EQ is likely to stop the silliness of trying to EQ your system with cable swaps, component swaps, funny things that go under other funny things and so on.

I'm beginning to think that the elimination of early tone controls (yes, I know, cheap parts, bad circuits but why throw the baby out with the bathwater) was a savvy idea in the early days of high end to keep folks changing gear when all it would take is a few turns of a few knobs.

Anyone that can't/won't optimize speaker and listening position per Jim Smith's Get Better Sound or any other tried and true method must try one of these. I insist. Cult leader Jason Stoddard can thank me later.

BTW, the tide is turning. I’m seeing more and more very well designed EQ functions in modern line stages. One example would be the Zesto Leto. Included is a six position, remote controlled "Presence" control. No getting around it, some recordings are going to be edgy, aggressive or bright because someone wasn’t doing their job properly during tracking, mixing or mastering. A very nice and useful feature. Interesting to note the designer was a well regarded recording engineer for many years while the rest of us were being brainwashed through these audiophile forums.

When an audio designer is deciding on what turnover frequency will be the most likely effective to the most systems, it is a gamble. Say for example a bass tone control. Ok, where will the turnover frequency be set? I have seen them set as low as 20hz all the way up to 120hz. If you give the consumer a choice of 3 different possible turnover frequencies, 30hz, 50hz, or 100hz, then there is a greater chance that the control can do a more effective job with your system. Same of course with treble. Maybe 3khz, 6khz, or 12khz, etc. 

  Maybe the best that I have had was by SAE, which used a two band per channel parametric EQ.