The new Select LSA/HPA rotary switch and PCB allows you not only to select where the output signal goes, but which capacitors are used. Headphones, even high-impedance ones, such as the 300-ohm designs from Beyer and Sennheiser, require fairly large coupling capacitors, say 30µF; but line outputs usually use coupling capacitors that range from 0.1µF to 4µF. In addition, the big coupling capacitors that attach to headphones, are usually only very good, whereas the smaller coupling capacitors that attach to our power amplifiers are usually much better although smaller in value, but not always in size.
Well, with the Select LSA/HPA switch, we can use both types of coupling capacitors. For example, in a LSA/HPA project hat I just finished, I used both a 30µF and 1µF coupling capacitors. The line out got just the 1µF capacitors, while the headphones got both in parallel, with C1 being the 1µF capacitor; C2, the 30µF capacitor.
The rotary switch present three positions, so the center position is mute, for both headphones and line outs. The 1.4 by 1.8 inch PCB hold a single rotary switch and nothing else, other than termination pads for hookup leads.The PCB are made in the USA and are thick (0.93in) and hold heavy 2-oz copper traces.