Equalization

Most buy their speakers for the sound they prefer and don't need/want to add filters(tone controls), which can detract from sound quality, as well as interfere with internal crossovers in the speakers.
B

Hmm that is interesting.
So people use no filtering and just let the speakers speak on their own?

Yup.
I bought my Vandersteen Treo's for their sound and capabilities and incorporated amps/preamps/DAc's that work well with them.
For the most part, I have no desire to alter their sound reproduction. They reproduce music as it was recorded. Any deficiencies are mostly due to the recording.

There are some digital EQ systems out there to correct room response, but are rather expensive.
B

With limited exceptions, having tone controls/eq in the circuit is thought to cause a degree of corruption to the signal that takes the system a step away from the realism that is the end goal of a high end audio system.