How to build an Objective2 Headphone amplifier.This is such an awesome project that I hope that someone might see this and 'get off the fence' and build one. It's a great first project, but it has such fantastic performance that even the most diehard DIYer will be extremely pleased with it.If you are not familiar with the O2, here is some more information -And this link has all the really good information in it for the DIY constructor -One of the reasons that this project is so good, other than it's very good design, is that it is documented better than just about any other DIY project ever. Just about all your questions are answered by the designer himself. It is wonderfully beneficial to read the above all the way through before starting construction.This is my visual build log for the O2.This is the board in it's empty state.The Box Enclosures box and the faceplate, purchased from JDS labs. See this page -- JDS Labs - Store - DIY Parts Here is a good photo for scale, 2 normal 9v batteries.And this is the small AC wall-wart for charging or playing. With the amp playing on either the AC supply or the internal DC batteries, it sounds the same.Some (but not all) of the various components to go on the board.That is everything sans enclosure and batteries.It is absolutely imperative that you check and double check the locations of the items as you stuff the board, and measure everything that you have the capability to measure before installing it.Most of the specified resistors are these cute tiny 1/8 watt items, shown with a 'normal' 1/4 watt Dale for comparison. Also look at the PCB and see one installed. You don't want to remove one of these if you don't have to.I made one error when ordering, where I entered a quantity of one when I needed two. So I replaced both with a bigger (1/4w) resistor, seen here mounted 'soldier style.'If you have bunch of 1/4w resistors on hand I see no reason why you couldn't use them mounted as such in all the locations where a 1/8w would go. There is plenty of room.I ordered my parts from Mouser, merely copy and pasting from the published BOM into the order page on Mouser's site. When you order, there is a place for you to enter a 'customer part number' which is a great time to label the parts to match the board.The 2 circles are my pattern to cut down on stuffing errors - the top circle is to match the part description against the BOM. The bottom circle is to verify the value printed matches what I measure it to be. It doesn't take much time, and cuts errors way down.It's always a good idea to leave a bit of room between the board and PSU filter resistors. They get hotter than the other resistors.Diodes match the board, put the striped end (of the diode) on the striped end.(of the board)I forgot to take a photo with just the resistors and nothing else. Oh well… The ceramic caps (the yellowish ones) are next. As always, we will stuff the board smallest items first, then the next bigger, and so on.The next components are the blue film caps and the DIP sockets. (for the opamps)The regulator pieces are next, they are also polarized, the heavy white line of the board shows the back (tall and or flat) side of the power devices.And there is the proper orientation of the device.The can capacitors have the potential to blow up if installed improperly. They are polarized, and even marked twice -- the long lead is the positive, and the stripe with the " - " sign is the negative.The pads for the caps are also well marked, the + is clearly visible, and also you can see the bit of heavier line on the circle, to mark the negative. That's a very nice touch.Again, where you have a can cap, you will see those markings.By this time you should have the bulk of the board stuffed minus the edge with all the jacks.The AC plug supplied didn't quite fit the holes in the board. The supplier probably made a change recently without telling anybody. Oh well. You can see where I filed the connection down, to let it fit smoothly on the PCB.It seemed the most logical to stuff the components on the edge from the bottom to the top. It worked well, and nothing interfered with anything else. Easy!In every photo of the PCB on NwAvGuy's site, the watermark completely obscures the battery terminals! Anyway, it is supposed to look like this.you are ready to do some testing. Go to this page - NwAvGuy: O2 Details Scroll down to the photo of the Multimeter and start the testing procedure!~~~~~~~~~~~~~~~~~~As mentioned in the build guide, if the solder pins are not cleanly trimmed it will snag on the case.don't remove the center front pin because…You need to attach a wire to it to attach to a bare parch of the case via a panel screw. A thin wire or a trimmed component lead will do nicely here.Here is the O2 playing music for the very first time. It looks great! Interestingly, my phone was playing the music and taking the photo… Cool.The O2 is completely silent and sounds fantastic!EDIT -Here is my amp with a Stainless Steel faceplate from member 'Yangoran'It looks great!!