Been sending music around the house with iTunes and Airport units for a couple years now. I started with an old mac G4 tower, upgraded to an mac mini, and later got a deal on a 2009 quad core macpro. For the Wifi I started with the old white saucer shaped Airport base station, and a few years later I grabbed a flat pan 802.11N style Airport Extreme off the DC craigslist. I wound up with a couple of the wallwart style Airport Express units, and have replaced them all so they are all 802.11N generation as well. Tho none are the latest hardware, they all work well in our multi-floor home. After the initial start with an internal drive in the G4 tower, I played with various configs of external drives, which make backups and upgrades much easier to deal with. I tried single and dual drive units, but I currently use a nice 4 drive unit from Amazon. I had a dedicated card and was using eSATA, but the chip vendor did not make a driver for OSX 10.8 - mountain lion, so I switched to USB, fast enough for lossless music. A few years back I decided to upgrade the music fidelity, and went through a long process of reloading all my CDs in Apple Lossless Audio Compression. we do have some tracks purchased from Amazon or iTunes that are lesser fidelity, but most of the 40k+ tracks on the drive are lossless. Apple lossless works great and it allows album art and such on our portable devices (iPod, iPad and iPhone) as well as in home, so I don't want to go to FLAC, WAV or AIFF. But this long intro brings me to the latest quest for the gear. Hadn't thought much about it but i had always run a standard mini-headphone to twin phono type audio cable from the Airport Express to my preamp. After some reading here I heard an easy upgrade was to pull optical from that Apple mini-jack and feed that to an external DAC So just before Christmas, I bought a very affordable gadget from Amazon, the $20 FIIO D3 DAC ... a tiny little thing with cables and power supply! Its the black gadget to the left in the picture below. Anyway, it was an amazing, eye opening upgrade. Bass tightened up, kick drums became more drum-like. i could hear shimmer on cymbals, breathiness on vocals - all kinds of detail just appeared. Best $20 I ever spent on Audio! The most amazing thing appeared when I played some old grateful Dead live recordings I had gotten from Archive.org a few years back and converted to Lossless from their default FLAC format. I had a soundstage. There was the audio image of the band front and center in the room. I'd heard imaging before with a pair of magneplanar speakers I owned, and with the DCM speakers I played with last year - but not with these heavily customized JBLs I now own. Not all albums do it, but for the ones that do play that way, its the way I always want to hear them now! So - if a $20 DAC can do this, what if I get serious and get something more upstream. I'm on a budget, so there won't be any thousand dollar DACs in my future ... I'm figuring under $500 and under $400 is really more my comfort zone. I don't need a DAC with tubes as I am using a Jolida JB502 BRC integrated (tube) amp, no need for more tunes in the system, the Jolida is a great amp. Any DAC I get needs an optical in for the Airport signal, plus a second optical or Coaxial in would be nice when I play CDs and such in our OPPO 981HD disc player. I don't need USB in as we don't have a computer in that room - but its ok if it has one, systems change and you never know what you may want a year or so from now. One consideration - any DAC I test should be at LEAST as transparent and useful as the $20 FIIO D3 I tried at Christmas. I also expect the same kind of imaging I heard on those specific tracks I mentioned in the previous post. If I spend more money than the $20, I expect better results. More info as this thread progresses.