While the problem seems to be gradually resolving itself, let me add a few comments.
First, though I apologies for asking, is the speaker actually Bright or harsh, or did you simply read somewhere that metal tweeter are harsh, then incorporated that into your belief system?
To say a speakers is "Bright" implies an imbalance that doesn't suit your ear. Bright is more treble relative to the amount of bass. A tweeter that is a bit bright without being harsh, might be called Crisp. To make the distinction, do you actually hear crisp detailed sizzle in the cymbals, or is it more of a generic hiss?
You can soften Bright treble by dialing it back a bit, but you can not do that with a single resistor. If you use a single resistor, you are changing the perceived impedance of the tweeter as seen by the crossover. That will cause the crossover point to shift and either leave a gap or cause a peak in the response at the crossover.
So do this right you need an impedance balance L-Pad, as seen in the diagram below -
The values for of R1 and R2, you can use an L-Pad calculator as seen at the bottom of the next link -
Crossover Design Chart and Inductance vs. Frequency Calculator(Low-pass)
There are indeed metal dome tweeters that can sound harsh, but equally there are cone and dome tweeter than can sound harsh, and further there are metal dome tweeter that can be sweet as silk. The Canton speakers use all metal drivers - bass, mid, tweeter - and I did not find them the least bit harsh.
One problem with any metal driver is that while they sound fine within their working range, they typically have a massive break-up region above the working range. This can be seen in the frequency response graph of this Dayton reference woofer.
http://www.parts-express.com/pedocs/specs/295-355-dayton-audio-rs180-8-specifications-47079.pdf
Notice everything is fine up to about 5khz, then the speaker goes a bit crazy. These are very good sounding drivers, you just have to make sure you select and design the crossover to suppress this breakup region.
I suspect the same thing happens with metal dome tweeters, but the breakup region is well outside the range of human hearing.
Lastly room acoustics. Someone said room acoustics don't effect mid/high frequencies, when in reality they effect the Mid/High range most. Most of us are used to a Slap-Back echo, where you shout into a canyon "Hello" and a fraction of a second later you hear the canyon shout back "helloooo". In a typical room, the time delays are far too short to hear a slap-back effect, but echo is there none the less. This can cause timing errors especially in the treble range.
At the following link you will find some information about room acoustic. Pay specific attention to the video in Post #8.
Primer: Acoustics - Absorption & Diffusion | AVForums
This is an Australian guy who does pod-casting, mostly of just him talking. He is in a small room, but at the end of the video, he does a before and after acoustic treatments. Though his professional mic does not pick it up well, you can clearly hear the echo in the room on the camera microphone. His needs were limited to voice, so relatively shallow acoustic panels did the job for him.
The simplest way to evaluate room acoustics is to simply look around the room. If it is all hard surfaces, no curtains, no carpets, no clutter, then it is probably an acoustic nightmare. On the other hand if it is an old fashioned soft furnished, carpeted, curtained, cluttered room, the acoustic are probably much better.
Because of the timing errors, indeed a highly reflective room can make treble harsh.
Lastly, AV Receivers. The problem with most AV Receivers is that the Power Supply can't keep up with the Amps. In a recent review, a common and popular, and seemingly powerful AV amp only put out 30w/ch when all SEVEN Channels were driven equally. Frequently, an 700w total AV amp will only have a 500w power supply, that means no combination of channels can ever exceed a total of 500w.
That's somewhat OK, because in an AV Surround System, the front three channels carry the bulk of the weight. The Side/Rear channels don't strain all that much. So, you virtually never have equal demand on all the amp channels.
But, a typicial 100w/ch Stereo amp will have a 300w power supply, given massive reserves of available power. Many of these Stereo amps will have huge banks of Capacitors on the power supply giving massive short term current capability; 40 amps to 60 amps short term would not be unheard of. Just to illustrate, if we push 40 amps through 8 ohms, the equivalent power is 12,800 watts. That's not realistic, it just illustrates what a 40 amp short term current reserve means. It simply serves as a point of perspective.
Again, the conversation seems to be winding down, but I though I would add these points.
Steve/bluewizard