Back in January, I reviewed Wyred 4 Sound's excellent mAMP. To form a complete system, power amplifiers like the mAMP need to be tethered to a preamp. Enter the companion model, Wyred 4 Sound's mPRE stereo preamp, which not only shares a similar price ($1,099) as the monoblock mAMP ($999) but is even housed in a similarly sized and shaped metal chassis.
Given the high level of performance of the mAMPs, I had high hopes for the mPRE. Except for some problems at the beginning of the review (which were solved by Wyred 4 Sound's fast-reacting R&D department), the mPRE by and large lived up to the promise of the mAMPs. For audiophiles who want top-tier sound and solid build quality at real-world prices, the mPRE and mAMP deliver a made-in-the-U.S. solution that's easy to live with.
A preamp has three primary functions: to adjust the volume level via a volume control, to select the source via a source-selection switch, and to send the signal to�your power amplifier. The mPRE offers more than a bare-bones preamp function by including a digital-to-analog converter (DAC). The mPRE accepts up to a 192/24 sample/bit rate on all of its digital inputs: S/PDIF, Toslink (if supported by your computer), and USB. Along with its three digital inputs, the mPRE provides three analog inputs: one balanced XLR and two single-ended RCA. One stereo RCA input can be converted to a stereo pass- through via a rear-mounted push-button selector switch.
The mPRE has three pairs of analog outputs: one balanced XLR, one independently buffered single-ended RCA output that runs in parallel with the XLR outputs (its volume level changes along with the balanced XLR), and the last pair of analog outputs can be used as either a variable or fixed-level output selected via a second, small push-button on the back of the mPRE.
Inside the mPRE, you'll find a fully balanced analog circuit from input to output (for the balanced XLR input; single-ended inputs are changed to a balanced signal by the mPRE). The analog volume control is very similar in layout and design to the one created for Wyred 4 Sound's flagship analog preamp, the STP-SE, featuring completely separate�right- and left-channel topology even at the power supplies. With over 80 FETs in a parallel scheme, the mPRE's dual-mono, dual-differential design was created to rival the best preamps regardless of price or design layout.
The mPRE's digital section is based around the 9023 ESS Sabre DAC. This DAC chip is combined with an XMOS asynchronous class 2.0 USB interface to deliver driverless connection for the MAC, but requires a supplied dedicated driver for Windows PCs.
The 0.75-inch-thick aluminum front panel of the mPRE is simple and businesslike, with a centrally positioned master volume switch flanked by three input buttons on each side. Underneath the volume control is the window for the remote sensor, and on the lower left corner of the front panel is the mPRE's 0.25-inch stereo headphone output. The back panel contains all six inputs, three outputs, a 12-volt trigger input and output, the AC receptacle, and the main power switch.
During day-to-day use, I found the mPRE's simple mini-wand remote control to be very handy. Although it includes only an on/off button, up/down input buttons,�up/down volume buttons, and a mute button, the remote supplied all the functions I needed. Although some stepper-motor volume controls I've used in the past have been either too slow to respond or hypersensitive, the mPRE's volume was just the right balance of a fast response time without excessive or overly rapid volume boosts.
I mentioned the two push buttons on the back earlier in the review. Although I appreciate the flexibility that the two switches provide - permitting a home theater bypass and variable/fixed level for the third analog output - the buttons themselves are somewhat problematic. They are simply too easy to push while attaching and removing cables from the back of the fully populated rear panel. I would prefer a sideways-moving switch rather than a push button because it would be harder to accidentally push.
I heard three different mPREs during the course of the review. The reason for the multiplicity of review samples wasn't due to any operational failures, but because of a potential problem with the mPRE's headphone output. The first unit I received had noticeable noise when mated with higher-sensitivity, low-impedance in-ear monitors. Wyred 4 Sound sent me a second sample to determine if it was an�individual or universal issue. After I found the second unit had the identical noise level with certain headphones, Wyred 4 Sound went back and re-adjusted the headphone output circuit to reduce the noise level when using high-sensitivity headphones. A couple of weeks later, the third and final review sample arrived. The latest version still has a slight amount of low-level noise (principally low-level 120Hz hum coupled with a slight buzz) with my custom Westone ES-5 in-ears, but it is dead-silent with every other headphone I tried.
Click over to Page 2 for the Performance, High points and Low points and Competition and Comparisons, and the Conclusion . . .�