hifijunky
New Head-Fier
- Joined
- Sep 26, 2013
- Posts
- 21
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As a general rule, tubes amplify with higher voltages and lower currents whereas transistors are the opposite, lower voltages and higher currents. The power (watts) delivered to the load (headphones in this case) is the product of the voltage multiplied by the current. Current flows easier through low impedance headphones (orthos/planers) and requires lower voltages to produce a specified power rating. Conversely, high impedance headphones generally require a higher voltage to produce enough current to achieve the same power output. OTL designs can't produce the necessary current into a low impedance load to reach satisfying power levels (volume).