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Go look up some datasheets for Bluetooth chips. In fact, here are some datasheets for you:

http://ww1.microchip.com/downl... http://www.bluecreation.com/fd...

15 to 30mA for music streaming, which depends on range and how crowded the 2.4GHz band is. There is no getting around this, no amount of clever power management will help. Radios use power, Bluetooth mandates the time that the radio must be turned on, it just can't go significantly lower. So no matter how efficient the CPU and everything else is, all day on 10% is impossible.

What did I tell you about JUST looking at datasheets and trying to infer an embedded SYSTEM's requirements/performance?

You are the one that brought BT into this. Apple's battery-life tests were no doubt done with no headset of any type, or with the wired headset. Of course, using BT earpieces would bring that down a little. Now, LynwoodRooster, who claims to be a designer of BT devices, sez the iFixit teardown of the iPhone 7 shows that Apple is using a Murata-branded BT/WiFi COMBO module (See step 15 of the teardown; which uses either a Cypress Semiconductor BCM4339 or a Marvell 88W8897 chip, so, that could (likely would) have a different current requirement from the Microchip and whoever-the-hell Bluecreation is; so your 15 to 30 mA figures may or may not be relevant. But even if that was a CONTINUOUS requirement (which I sincerely doubt it is), or just a rough-average, or an "absolute maximum", 15 to 30 mA is still not such a big deal to a 2900 mAh battery. 2900/30 = 96 Hrs at 30mA CONTINUOUS for your BT chips. I couldn't get a straight answer out of the Cypress Datasheet; but assuming it is no more than 30mA for the BT subsections, that shouldn't be a problem.

And of course, with aggressive power-management, that 30mA won't be anything like continuous.

Like Japan, Taiwan does a lot of high-tech manufacturing.

There is more than one level of high-tech manufacturing. It's one thing to take a 0402 capacitor and put it onto the PCB. It's a very different thing to make that capacitor from microscopic parts in the first place. Do you think there are no trade secrets in ceramics that allow you to cram a few uF into an 0402 part? (Murata is a Japanese company.) Even this tiny segment of passives is dominated by US and Japanese manufacturers (TDK, Taiyo Yuden, Kemet, Panasonic, Murata.) Even AVX, a very solid US manufacturer, has nothing to offer if you need 4.7uF in size 0402.

Companies like Panasonic-ECG and Rohm are doing very well, and they are producing very cost-competitive components. If you are looking for a low cost surface mounted aluminum capacitor, Panasonic is the most likely manufacturer.

After some Googling, it seems that the data acquisition Datel was acquired by C&D Technologies in 2004, which in turn was acquired by muRata in 2007.

The DAQ Datel was not some obscure company. They had the datel.com domain, which currently forwards to murata-ps.com.

If you use powered amplifiers, then you're running the signal through wire to the amp. Any noise the wire picks up gets amplified.

Some pro arena installations with exceedingly long runs such as a sports stadium in a location with lots of electrical noise (stage lighting, Mercury, lots of cellphones, and radio and TV remote broadcast) take the additional steps of using higher voltage so the noise pick-up component is a smaller portion of the overall signal in the wire.

Typical home stereo stuff uses about a quarter volt for interconnects. TV and Radio station studios use a higher level, which is often a balanced shielded connection to prevent ground loops and reject common mode noise pick-up.

http://www.murata.com/emc/knowhow/pdfs/te04ea-1/26to28e.pdf

Some pro sound installations go as high as 10 volts of signal from the console simply overpower the much lower noise pick-up on the wire.

Might want to take a look at these (Transparent Ceramic)

http://www.murata.com/opt/lumicera.html

They have refractive index of 2.08 and is for optical applications.

Indeed, that is the key point. From this list you can get an idea of the index of refraction of common materials. This ceramic glass has index of refraction of 2.08.

Presumably this ceramic glass has the advantage of being hard and have a very low cost, otherwise they might as well use cubic zirconia (index of refraction 2.17)

This might be a case of a solution finding a problem.

The lens is made by MuRata and is called Lumicera. Info can be found at http://www.murata.com/opt/lumicera.html

Comparison of Refractive Index between Transparent Ceramics and Conventional Optical Glass
The refractive index of the transparent ceramics is 2.08 (lambda = 587 nm). It is quite high compared with that of conventional optical glasses (between 1.5 to 1.8). Furthermore, as there is no birefringence in the ceramics, there is a potential for downsizing and advancement of optical devices with optical elements, such as lenses.