Thanks, I just checked and both tweeters are definitely working.Bite the bullet and buy a calibrated measurement microphone (umik-1 is like 100 usd). There is no quicker and more sure way to know exactly what is going on and all your other setups will benefit too. Just to be sure though, have you confirmed that the tweeter is working? Now that I see that the speaker uses very shallow crossover slope, it actually might not be obvious if it's not working. The tweeter may have blown (it's not very well protected by the minimalist crossover) or the jumper/link on the terminal is missing/loose.
In addition to my very damped room, I just realized that another factor that may at least in part account for my Lumina's not sounding very bright is the power amp I use. It is an older Krell FPB 400cx amp, which is a class A amp and I believe Krell may have intentionally designed these amps for that big ballsy but not bright type of sound. If this Krell didn't weigh over 100 pounds, I would swap it out with an amp known to be neutral and see how the tweeters sound.