Do Your Speakers have LEVEL CONTROLS or EQUALIZERS? (Vintage or Modern) ???

I have DT Mythos ST's with built in powered subs that have a volume knob for the subs

Sort of. In addition to the 2 stereo outputs, which run ESL's, I have two blended outputs with their own volume controls. These volume controls are downstream of the master volume control, and drive Magnepan DWM's. 

Basically it's an active crossover built into the preamp, so the effect is much the same - except for distortion.

Yes. Janszen Valentina P8 (a current model). Each has a woofer level switch, a level pot for the electrostatic panels, and a second level pot for the side-mounted tweeters that can provide more local ambiance if desired.

Yes, my FinkTeam KIM have two controls. They are very useful, and the first speakers that I have owned with such controls.

This is how they are described in StereoNet:

Two level controls are located beside the rear speaker terminals. One is a simple treble trimmer to reduce the tweeter level, while the other is a three-position bass damping control to help tune the KIM to the output impedance of the attached amplifier.

Apropos of this, Karl-Heinz [Fink] explains that: “When I was working on a high end floorstander, I found that the inductor on the woofer crossover made distortion that I could measure. So we changed to an air core with thick wire. This was no problem on the floorstander, but the next model we did was a bookshelf and so there was no space for a larger coil. I was running some simulations and found that I could modify the parameters of the speaker in the box with the magnet system and a higher resistance air coil. Yeah, school knowledge is that the inductor should have low resistance, but that’s not true. If you know what to do with your alignment, you can use small inductors and get good bass.”

Karl-Heinz then tried using a higher resistance inductor and another resistor in series to change the speaker’s alignment even more. “We can switch between 0.5 ohm, 0.25 ohm, and nothing, so this can be used to tailor your speaker to different amplifier technologies. A modern transistor amp has a high damping factor, so you use the larger resistor setting, while more traditional amplifiers like Naim normally use a smaller resistor in series, so the middle position is correct. And the left option is for tube amps; this works well with push-pull designs and helps with the bass.”