Audio Research Reference Two preamplifier
The fully balanced gain section, rated at 2V RMS balanced (maximum output is 30V RMS) and 1V single-ended, uses eight specially selected Sovtek dual-triode 6922 tubes, while the onboard power supply consists of a 5AR4 rectifier tube, with the resultant DC regulated by a 6L6GC and a 6922.
In place of traditional mechanical potentiometers or stepped attenuators, the volume and balance controls are spring-loaded on/off switches that control the electronic attenuator's 125 steps. Turn the volume control quickly in either direction and release, and the level rises or drops by a single step. Hold the switch to the left or right and the gain increases or decreases continually, measured by a succession of LEDs surrounding the gain and balance knobs on the unit's face. There are far fewer than 125 LEDs around the knobs—the level and balance can be changed by many steps before any change is reflected in the LED display.
Similar spring-loaded electronic switches control the eight selectable inputs and the seven-position tape-monitor facility, giving you the option of listening to one source while taping another. Four toggle switches control power, muting, balanced/single-ended in, and phase. Once configured, a memory feature automatically switches between single-ended and balanced inputs as you switch through the input choices.
The slim, compact remote control duplicates all of the front-panel controls except for the balanced/single-ended switch, which, after the initial input configuration, you won't need to adjust anyway. With volume and source remote-controllable, the Reference Two is a reviewer's best friend.
Continuing a long Audio Research tradition, the rear panel's right-channel row of inputs and outputs is placed above the left-channel row. Don't ask me why; everyone else does the opposite. Whatever: the chassis-mounted RCA and XLR jacks are generously spaced and easily accessed. In addition, there are two sets of Main outs, a Record out, and an IEC mains jack.
Everything about the solidly built Reference Two has been designed for the convenience of the well-heeled audiophile able to buy such an expensive product—everything but the 16 screws he or she will have to remove to get to the circuit boards and install the tubes. Hopefully that inconvenience won't have to be repeated for many years! While ARC thoughtfully provides a high-quality screwdriver, I was happy to have a a powered screwdriver (set to minimum torque) for the task.
Operation and Sound
The Reference Two is not intended to be left on continually, but about an hour's warmup time is needed before it's ready to give you all the music it's got. If you buy one and want to listen after a hard day at the office, switch it on before dinner—though it will play after about 45 seconds.
The remote is a pleasure to use, and, with its phase-inversion and input-selection capabilities, offers genuine 21st-century convenience. Thankfully, AR chose not to adapt a cheap, plastic mid-fi remote—an insult to the purchaser of a $10,000 preamp—nor did it encase the remote in a weighty, unwieldy aluminum sarcophagus. The Ref 2's remote is lightweight, unobtrusive, and won't tire your wrist muscles.
I used the Ref 2 in single-endd mode and once broken in and warmed up, the Reference Two sounded like anything but the proverbial "straight wire with gain." It definitely had its own sound. I confirmed this by connecting my EAD DSP9000 Mk.3 processor directly to the power amplifier via its internal digital/analog volume control, then through the Ref 2.