Now that I have my Mac Mini set up to deliver my whole iTunes library to my listening room through Airtunes with Sony PSP remote control, I needed to rewire my hi-fi components. The goal: deliver the digital Airtunes signal through the best DAC in the path and passing the analog signal cleanly through to my loudspeakers. I have no budget, so I must only use components I already own.
I also wanted to test how much I could combat the compressed audio feed’s nasties in the analog realm. My weapons: Taddeo Digital Antidote II and Rogue Audio Magnum 99 Preamp. One of these components won the battle and the other almost lost the whole war.
Airport Express DAC: Stereophile has taught us that the Airport Express’s internal DAC is to be avoided in a hi-fi set up. To successfully use an Airport Express in your signal path you must use its digital optical output feeding an external DAC. The Airport Express outputs a digital signal through the same mini jack port as analog. I just needed this mini-jack to optical adapter from Parts Express.
Digital Optical cable: My optical cable collection is the most neglected cable category in my home theater set up. I’ve read many articles and books (like Audio/Video Cable Installer’s Pocket Guide) lauding the optical cable. Digital coax is universally considered a superior connection—jitter reduction (or least amount of addition), and more stable connectors. So the best optical cable I have is not from a !33t boutique manufacturer but from Best Buy’s favorite: Monster Cable. I’m sure its price surpassed its quality.
With the mini jack adapter clicked in place I insert it into the Airport Express and then snake it across to my Onkyo’s Digital Optical Input 3 (formerly home to Dish HD STB audio output, soon to be sent back to Dish/AT&T for personal budget cuts).
Onkyo DAC and analog passthrough/output: It took me a couple tries to figure out the analog output from my Onkyo AV receiver the Airport Express feeds. My initial attempts pass the digital signal out through an analog out failed. I had to reference the manual to find out that you could not pass a digital only signal to either the analog record out or to Zone 2. I split the Onkyo’s preamp out to deliver the Onkyo DAC signal to my Rogue preamp. One pair of interconnects plugged into the Tape Input while the other remained in the AUX input (with the Rogue’s home theater bypass the AUX input is wired to bypass (duh) the Rogue’s tube gain and output stages). (I hope the Monster Turbine Y Adapters I use to split the preamp out are as transparent as advertised, a small bit of metal and teflon shouldn’t make too much difference, right?)
Problems with Taddeo Digital Antidote 2: I love my TDA 2 for CD playback. I thought for sure they could make compressed digital audio just as sweet as CD. I was wrong. Airtunes through the TDA 2 sounded compressed, congested, boomy, splashy, muted and just super awful. Since this was the way I first wired the rig I was quick to blame the Airport Express and compressed audio delivery. I almost gave up. Always suspicious that I’m doing something idiotic that I think is genius I took the TDA 2 out of the path. Someone just removed the thick veil covering the music.
Gain and Volume Control: When you attenuate digital signals you lose bits along with decibels. I wanted the cleanest signal out of the Onkyo while using the Rogue’s normal volume range. To achieve this I raised the Onkyo’s volume to its reference, 0 db. I kept the Rogue’s gain at the middle setting. This combo gave me manageable volume control on the Rogue with a minimal loss of bit resolution.
With all my wiring (and non-wiring) in place I was finally ready to sit in my listening chair and enjoy any song in my iTunes catalog.
Next: Listening tests and family dance parties.