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Design Goals
A quick reread of October's Circuit of the Month is a good idea, as it presents the argument for no voltage gain, but some current gain. The short recap is that passive line stages, although conceptually superior to any active circuit, do not always sound better than even an obviously less-than-perfect active line stage. By eliminating the gain portion of a line stage, however, we eliminate much of the distortion and noise of an active line stage as well.
Phase as an audio issue is hotly debated. Some think of it as the missing link to true musical reproduction in our homes. (In real life, all music is in perfect phase, even if the performance is mostly received from microphones and blasted through a mix of differently phased amplifiers. The phase of that total acoustical event is what we need to reproduce in our living room.) Others argue that the ear is insensitive to phase and thus phase preservation is a non-issue. The truth, as we usually find to be the case, lies somewhere in the middle; besides, options are always welcome. Noise, on the other hand, is not a hotly debated subject: everyone hates it. Noise robs a system of subtle nuance and obscures detail. In addition, it constantly reminds us that we are not listening to a live musical event. Here then is the design goal: no voltage gain, but a healthy output current delivery; the ability to flip the phase of the input signal; and extra low noise operation.
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