To add, how many channel in/outs are available with a single wireless receiver and what brands are proven to be stable?

Reading Sennheiser's line-up, there are a lot of systems but I'm not clear on what channels really mean? Do channels mean frequency channel options, as in choosing a single various frequency of a choice of many to find the best signal reception for one mono mic, or ... do channels mean, I could have 1> 2 > 4 > 8, or 16 mono mic transmitters feeding into it single 16 channel receiver that feeds those into my live console? Thus, having the ability to have 16 wireless headsets going in a live theatre production?

Also, I never found any diagrams of the rear panels to these receivers so I'm wondering how the receiver sends 16 channels of audio to the console?

Question three.

Is the transmitter the most critical component of the wireless system?

a lot of the higher end systems actually have control software (this is what is found on broadway and other big theater and tv productions). Normally one receiver one transmitter per freq. now there may be many freq available in a manufactures "channels", often notated by a numeric and alpha code (h5, j5). Keep in mind your area might only be able to have certain channels work because of radio,tv etc. So that can drastically reduce your options.
I would say the source would be the most critical component, depending on the amount of channels needed to run at once will dictate the level of wireless you need.
I found Sennheiser to have some of the best sounding and most reliable units.

We use 3 different wireless units when we jam. 2 shures and one audio technica.
1 shure T4A diversity VHF on guitar.(the best one i've heard for that).

I found that for guitar anyway, the quality of the units(transmitter and reciever) affects the sound greatly. We tried some cheap ones and you can really notice the difference.

For mics,i can't really tell if a better mic or a better reciever would make the most difference but none of them that i tried sound great.
Its hard to get good vocals from such a small diaphram. A lowly 58 sounds better all the time.
Having said that though,for live it does the job. jmo

Edit: I havn't tried any over $1000 though.

Do you want these headsets to be inconspicuous, or isn't that a factor? Most of the models made for high-volume stages have to be more directional. They're often larger and extend out further in front of the mouth - which makes them much more noticeable.

I haven't had an opportunity to try any of the Rode wireless systems. I didn't even know they made wireless until I saw your post. I like their other products, hopefully their headsets are as good. I'm also looking forward to trying the Audix wireless.

Budget wireless (below $500) is generally not a very good investment and you are very limited with how many systems you can operate simultaneously. Mid-grade and high-end is the place to be. A dual diversity system by any of the major players (Sennheiser, Shure, AKG) would be a minimum requirement. The main thing you need to address is, how many mics you're planning to use at one time.

You asked: "I'm wondering how the receiver sends 16 channels of audio to the console?"

It doesn't. This refers to the broadcast channel, (like your favorite radio or TV channel) not an audio channel.
The number of "channels" just refers to the number of available frequencies or sub-bands they broadcast on.

Some manufacturers will allow multiple receivers to share a single transmitter - but that is seldom very useful.

Going the other way and using multiple transmitters tuned to one receiver would be absolute chaos. Dual diversity systems are constantly comparing the signal from the two antennae and using the stronger of the two. If you had more than two or more transmitters moving around a stage competing to get into those two antennae you would have nothing but interference.

So, if you want individual control of 16 singers/actors, you will need 16 mics, 16 transmitter packs, and 16 receivers (each TX/RX pair tuned to a unique freq.) connected to 16 channels of your FOH mixer.

Most [="http://countryman.com/store/?catid=10"]Countryman[/]="http://countryman.c…"]Countryman[/] headsets are super small and sound nice. Plus you can choose sensitivity and directional characteristics to tailor them to your application (cardioid, omni, quiet speech, loud singing, etc). You really need to bend the earloop to get them to stay where you want them. Which might be ok for a singer, preacher, or anyone else who used the same mic regularly. For a rental situation, it might be a struggle to keep them in place unless you add the optional band that goes around the back of the head to rest over the other ear. Easily replaceable cable is a plus. And they're available with a variety of connectors to connect to any brand transmitter pack. (each manufacturer AKG, A-T, Shure, Sennheiser uses a different connector)

[[url=http://="http://www.akg.com/…"]AKG[/]="http://www.akg.com/…"]AKG[/] HC577 headsets use a thin frame that goes over both ears and are extremely easy to get consistent results. They cost a little more, and the capsules aren't quite as small in diameter, but they're still hard to see from 15ft away. The hard-wired cable would be a project to repair if it ever breaks. The cable on the older C477 was prone to breaking, the 577 strain-relief seem to be immensely improved - haven't had one break in years.

Also, think about batteries. Check battery life specs and if the transmitters require a single AA, two AA's, or 9V. That will make a huge difference in cost of operating them. Quality re-chargeables are something to consider too.

Perfectly explained, thanks everyone.

I've ordered RODE headsets. These will be mostly for speaking, theatre and the odd vocal if they work for that..
Now to start thinking about the receivers and transmitters.

What kind of connector did you get on them?

Good point. I'm getting multiple connectors so I cover a wide variety of transmitters.

I see they have detachable (interchangeable) cables which is cool. It's a relatively affordable way to change transmitter brand, and their corresponding connector preference, without the expense of a whole new headset.

I believe this is the same mic as the headsets but in the Lavalier.

Dvdhawk speaks of the batteries which is a big factor! 9 volt will cost big in the long run compared to AA or AAA for the As will last a lot longer.

Battery chargers are a must for headsets.They pay for themselves in a couple of months.
We use 2 headsets and one guitar transmitter.
Battery charger and 6>9-volt batteries= $75
1 hour charge.1 battery Lasts 2x3 hour nights.