Hard-disk–based audio systems having been gaining traction in recent months, with a half-dozen consumer electronics companies announcing or selling products. These new components model what savvy computer users have been hacking together for years—a software-controlled music library based on hundreds or thousands of CD or MP3 files stored on a hard disk.

Audiophiles know that cleaning up their AC supplies can yield a cornucopia of sonic benefits, including a quieter background, better retrieval of detail, and a subjectively wider dynamic range. The phenomenon is so well-recognized that it has spawned an entire industry devoted to making electrical conditioners, line filters, noise suppressors, and specialty power cords.

There's no question that the computer is at the heart of the recorded music experience for many people, but saving, sorting, and accessing digital music files can be a real chore. Now two Los Angeles technology companies have combined forces to create what they are calling "one-click" digital music management.

Most folks have enough room in their homes (some college students excepted) to easily place 100W amplifiers without regard to size or heat. But in the car, high-powered amps have always been relegated to the trunk or under a seat, often requiring creative solutions for anything with real heft.

Audiophiles almost universally agree that hearing—or "auditory perception" to neuroscientists—improves with practice. That phenomenon would explain why many of us are able to hear differences between audio components that untrained listeners can't hear.

From the March 2001 issue, Michael Fremer finds that, although homely in appearance, the <A HREF="http://www.stereophile.com//amplificationreviews/441/">Herron Audio M150 monoblock power amplifier</A> has several endearing qualities. As Fremer explains, "Herron approaches the marketplace in a cautious, stealthy manner, working from the ground up to grab the ears of audiophiles." MF tells us where this amp grabbed <I>him</I>.

Sony describes the $700 TA-P9000ES as "a pure audio multichannel preamplifier equipped with two inputs for 5.1 analog multichannel audio sources, enabling selection, volume control, and amplification." A relay with twin gold-plated crossbars switches the two six-channel sources. Then follows a class-A solid-state push-pull amplifier in discrete configuration. Separate transistors, resistors, and capacitors populate the printed circuit boards. An oxygen-free copper shield surrounds each channel to prevent crosstalk between the channels. In addition, there is a relay-controlled gain stage offering 0, +6, and +12dB amplification.

Sony describes the $700 TA-P9000ES as "a pure audio multichannel preamplifier equipped with two inputs for 5.1 analog multichannel audio sources, enabling selection, volume control, and amplification." A relay with twin gold-plated crossbars switches the two six-channel sources. Then follows a class-A solid-state push-pull amplifier in discrete configuration. Separate transistors, resistors, and capacitors populate the printed circuit boards. An oxygen-free copper shield surrounds each channel to prevent crosstalk between the channels. In addition, there is a relay-controlled gain stage offering 0, +6, and +12dB amplification.

Sony describes the $700 TA-P9000ES as "a pure audio multichannel preamplifier equipped with two inputs for 5.1 analog multichannel audio sources, enabling selection, volume control, and amplification." A relay with twin gold-plated crossbars switches the two six-channel sources. Then follows a class-A solid-state push-pull amplifier in discrete configuration. Separate transistors, resistors, and capacitors populate the printed circuit boards. An oxygen-free copper shield surrounds each channel to prevent crosstalk between the channels. In addition, there is a relay-controlled gain stage offering 0, +6, and +12dB amplification.