Are 800ohm or hi impedance speakers desirable?

Possibly yes.


They are not current hungry.


(Neither too voltage hungry, around 600Ω is neither too high or too low impedance.)


Bipolar transistors are current gain devices.


So just a transistor can be used to drive a 800Ω speaker directly from a CD line output.


An example signal path:


Sony D-EJ758CK - 2N3053 operating in class A - Philips AD5046N directly connected to the collector.


Also the collector current, thereby the battery supply current is low which is good news for battery operating time.


The above setup can operate with a 9V battery.


How about 10KΩ voice coils so that direct electron tube anode connection is possible. Or how about a low impedance triode 6A3 etc to a 800Ω voicecoil? Or perhaps lowering the impedance of electron tubes at low voltage by a high Megohm anode to grid resistor as on the Pleiades V6. (Any voltage can be dangerous. At your risk, all safety precautions should be strictly followed).


Another advantage is that the speaker cable can be thin.


Very simple class A operating amplifiers can be designed around hi Z speakers.


On the above example the power consumption and power output is very low. Typically 60mW consumption. 30mW of music.


Yet the sound quality is prestine and the sound level acceptable.


Why?


Possibly because of the logarithmic response of the ear brain to sound intensity. By the way these amps are great for learning to sing as low intesities make the human brain to perceive the correct pitch.


And to the fact that most music is on the average around the zero crossing point. A place where class A amplifiers (electrons flowing all the time) excell.


At peaks there is gradual distortion. Many systems of nature are non linear at large signals and linear at small. The ear brain is no exception. The loud signals which of course are limited by the non linearity of the amp and the brain ear is fooled that something loud is there.


Bibliography:


Sound and Hearing - Smith, Warshofsky - Time Life science series


Tubes bs Transistors is there an obvious difference? - Russel O. Hamm - JAES


Electronics, a systems approach - Neil Storey