In use, the Line I DT was very quiet and delivered detailed, harmonically rich music that was continually delightful to listen to. Vocals soared, cymbals rang true, and strings shimmered. With a powerful solid-state amp, such as my Halo A51, the Line I DT proved capable of convincing bass performance, too. Its parallel outputs made bi-amping easy.
I also used it as a signal conditioner (or buffer) between digital source and preamp, an ideal application. My usual CD playback arrangement is a Marantz changer whose digital output feeds a Perpetual Technologies P-1A reclocking device, whose digital output feeds a Perpetual Technologies P-3A upsampling DAC, whose analog output feeds a Margules ADE-24 “Magenta” harmonic sweetener. The Magenta’s output feeds a stereo input on my Halo C2.
I substituted the Line I DT for the Magenta and thoroughly enjoyed the results. With the volume pot in the 11 o’clock position, the Line I DT is a unity-gain device (output voltage equal to input)—a good starting point if you were to use it to add some tube-analog sweetness to CD playback. It’s phase inverting, however, and if absolute polarity is a concern for you, you’ll need to correct this by reversing your speaker wires at the amp or speakers.
Of the three ASL products, the Line I DT was my favorite and one I’d most likely use, either in my main system or in the office. There’s always a place for a tube buffer. The Mini Phono II DT phonostage is nice, but not something that holds any appeal for me—vinylholics on a budget should ignore my opinion on this.
The AV-25 DT power amps actually offer good value for the money, and are recommended if you have high-sensitivity speakers and aren’t concerned about visceral, authoritative bass. They work well in a bi-amp setup driving midrange and tweeter, with a solid-state amp supplying bottom-end horsepower. That’s the only setup that would provide me long-term satisfaction.
However, music lovers seeking authentic retro sound shouldn’t care about visceral, authoritative bass. Until late in the 20th century, the only way you could get it was from tubas, kettledrums, and cathedral organs.