I'm new to this whole speaker taps to power headphones thing,
I wanted to ask if anyone is familiar with the yamaha A-S500 and using it to power headphones such as the LCD2, and if there is any glaring error with doing this.
--- assume i know nothing,
Because as it happens, i don't.
You know as much as I did 8 months ago, which means you know to ask the question.
That Yamaha amp should be able to drive the LCD-2s, with no risk of hurting them, because Its 85-wpc power output into the cans' 60 ohms will be less than the power that the Audeze's can handle. This risk assessment assumes you can correctly connect the speaker tap to the amp speaker outs and the tap to a balanced (XLR) Audeze cable.
The sound quality will depend on whether the hardware is a good match. You might get great sound with no noise, or you might get crappy sound with lots of noise. You can't fix the quality of the sound -- the combination either meshes well or it doesn't, but you can fix the noise problem by putting resistor circuits between the amp and the speaker tap if necessary.
Resistor circuits would also give you more control over volume. Depending on gain throughout your system, you might have sufficient volume control without resistors... or you might go from 0-100 dBs with just a tiny bump. You could do a bunch of analysis... or you could just try it -- again you can't hurt the cans and you can protect your ears by just powering everything on at zero volume and carefully dialing up until it gets too loud. If it gets too loud too fast for your liking, then add resistors (they are cheap -- <$5 each). There are pictures of how to do it earlier in this thread.
So if you want to try this, you need to get a speaker tap, basically a 4-wire piece of cable (some of us just learned recently that you want unshielded cable) with a female XLR plug on one end and the connectors of your choice on the other end (bare wire, banana plugs, or spades... depends on what you like or are willing to pay for). Pretty much anybody that makes cables can make a speaker tap, or you can do it yourself.
Then you need balanced HP cables to fit the LCDs. You could go directly from the HP to the amp, but that means making a separate Audeze cable just for speaker amps, and swapping it if you decide to listen to another amp. Again, any cable maker can make you a balanced Audeze cable, or they sell their own for $80 (the LCD-3 comes with both types of cables... that's the
real reason why they charge an extra $1K for the cans...
).
That's really all there is to it. Except of course that you have to report back here how it sounds...
). My LDR isn't quite stock configuration. The beauty of DIY 
