As I listen to more music with headphones, my ears becomes more sensitive to a very high frequency near 16khz which seems to be "common" in many tracks. The intensity and actual frequency varies a little, and currently i have a quite large notch filter set by a VST, but I thought it might be more appropiate with a DSP that was able to read a tag for the notch.

Say you set a tag NOTCH with the following properties:
freq,width,gain

Anyone else see a use for this, or should I just wait to get old enough to lose that part of my hearing?

Man, that is a great idea. I have been thinking of getting my brothers carver speakers and bi-amping using the computer as a crossover, but they need notch filters.

Your idea would allow me to get rid of the passive notch filters and get better control of the speaker.

Actually I don't think you're searching for a notch filter, but rather this

Not actually. I do use this plugin, but the carvers have a notch filter in addition to the passive crossovers. SO if I was to use the foobar plugin you link (which I am using right now) I would still have to keep the notch filter components in the chain. The notch filter is there to deal with some ringing of the ribbon around 5k.

From the B and G site:

Recommended Notch Filter Use and Application
For optimum performance of the BG RD series drivers, it is recommended that a
simple notch filter be installed. This notch filter corrects for cavity resonances
between the magnet structure and the diaphragm in the 5K to 6K range. The
notch filter is placed in the positive signal path prior to the RD element and can
be used in addition to other crossover elements. To achieve a flat frequency
response throughout the entire spectrum, please use the following notch filter.
Values are as recommended by BG and may be customized to personal taste.

Doing this with software in addition to crossovers would be nice!

This wasn't a great idea after all?

foo_dsp_vst exists. Millions of vst dsp exist.

I know. It works... but not efficiently.

Keeping the defined settings is hard if the VST does not offer a way to save it.

My point is to remove 16khz of only annoying tracks. I've found some tracks are REALLY annoying and need a large notch, while others vary quite much in the frequency. As a result I found myself using such large notch that it seriously affected listening experience. That's why it would be nice if some component was able to read a specific tag with info for every track.

A way to solve it could be utilizing the EQU2 tag that stores custom EQ curves with a rewritten EQ DSP.