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Don't smirk, but a lot of audiophiles, including this writer and our esteemed editor John Atkinson, spend a considerable amount of time listening to music on their computers, especially at work. In fact, the results from our recent online poll about computers and listening habits indicate that at least 60% of our readers listen this way as well, with half of those using their PCs for music playback "quite often."

High-end audio equipment designer Ron Sutherland says he, too, found himself listening to his office PC often enough that he started to tinker with the audio possibilities. "When we go to the office, we leave behind our good-sounding systems, and the music is from the PC, using sources such as CD, MP3, and webcasting. Personally, I'm getting a big charge out of MP3 webcasting, but the sound cards are at the low end of low-fi."

Sutherland explains, "Inside the computer it is electrically very noisy, which is a bad environment for a sound card. Sound cards are also typically built to be cheap, with no budget for audiophile components." So, Sutherland says, he started to look at the data rate on the USB bus, which is the same as CD at 16-bit/44.1kHz, and decided that this might be "an acceptable data path for good audio."

After several weeks of development, he created the 12dAX7 preamp/DAC, which is connected to the PC via the USB port. Sutherland emphasizes that he's included "all of the 'politically correct' audiophile details: Wima polypropylene caps, Dale metal film resistors, toroidal power transformer, double-sided fiber-glass circuit board, minimal signal path, and on and on. But the real kicker is that the gain stage uses a premium Sovtek 12AX7 vacuum tube, and the thing is sounding very fine."

"Filtering is LC passive and the volume control is an analog pot, so there is not the bit shedding associated with digital attenuators," says Sutherland. "The 12dAX7 has full signal resolution at all listening levels." It is 15" wide x 9" deep x 3" high, and Sutherland says that it "looks like the high-end component that it is: steel case with a ½"-thick machined Lexan front panel with a window, so you can see the tubes inside."

The price for the USB preamp/DAC is $1495 and Sutherland says that it has just become available from a new dedicated website. "I see the market as music lovers with good systems at home. They spend a lot of time at the office and would enjoy good tunes there also. The PC is ideal as an MP3 jukebox, or using CDs and webcasting. Sound quality can go way up by using the 12dAX7 with a good power amp and good speakers, because the tube gain stage smoothes out the signal, making a huge library of music very listenable and enjoyable."

Sutherland adds, "Since building the prototype, I use it all day, every day. I'm getting more use and pleasure out of this than anything I've ever owned. It's so much fun to have access to so much new music."