Spectrum analyzer?

The spectrum analyser in the Behringer DEQ2496 will do the job for about $350 (including the microphone). 1/3 octave.
What's more, it can fix your problems once you have figured out what they are.

If your equalization requirement at some frequency is a "cut" rather than a "boost" the "feedback destroyer" function of the DEQ2496 can do 1/10 octave resolution.

Actually the DEQ2496 can simultaneously implement several sharp (1/10 octave) notches, several broad (multi-octave parametric equalizer) curves, and the 1/3 octave (31 band) graphic equalizer. It does not chew gum.

Kr4...The Behringer DEQ2496 autoequalization process gives the user a choice of FAST, MID, and SLOW response. Doesn't this answer your point about delayed reflections?

I use the FAST so as to quickly find the appropriate curve, and then switch to SLOW for the final tweak.

Kr4... No. But what would you do about it if it did?

But Kal...How would doing that make my system sound better?

Kr4...Thanks for your answers. Is there any device that can equalize delay at all frequencies? Anyway, I question your statement that delay should be uniform across frequency. In a highly reverberent hall, where delay is easy to hear, the tonal quality varies greatly as the sound dies away. In fact this variation is an essential characteristic of such sound. It wouldn't be realistic if it didn't happen that way.

Kr4...You say "Corrections based on RTA, only, are chancy."

Perhaps, but the $350 I bet on my first DEQ2496 has paid off better than any other expendature on my audio system.

As the saying goes "Don't let the search for perfection prevent the very good".