Here's the first:-
It's no more than the headphone amp reference design from the LME49600 datasheet with the addition of dual regulated power supplies. There is a slight departure in that the servos don't use amps from a second package, but rather each channel comprises one LME49600 + one LME49720. This simplifies and compacts the layout somewhat:-
This is a step on the way to a more comprehensive integrated desktop amp (including volume control, PSU and offset protection on a single PCB), but I think it makes an interesting stand-alone module. It'll probably fit in 50 * 50 mm.
And +/- rails shown for L/R channels for clarity:-
I'd obviously prefer to route the power rails superimposed, but the tracks are hardly extensive and no PCB is without compromises.
Unlike a lot of stuff I do, it's not really suited to homebrew PCBs due to the PTHs and via-in-pad construction employed, despite the fact that all but one of the second layer links are straight. I still have to get the LME49600s in my hand to verify the footprint.
I'm toying with the idea of doing one with only LM317s aboard but since I'm currently aiming at using a single AC wallwart I don't have the luxury of a dual-secondary-type supply.