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Looking exactly like the mINT from the front except for the obvious silk screen changes (the mute switch became the XLR input) the mPRE trades its speaker outputs for balanced i/o ports whilst the mINT's programmable fixed-out/main-in ports become a fixed/variable output instead. Otherwise the external packaging is identical as is the skinny long remote wand.

Basic performance specs are a brilliant noise floor of <12μV, channel tracking of ±0.02dB, crosstalk of >118dB, S/N ratio of >105dB and THD+N of between 0.002% and 0.006% depending on used socketry. Gain varies likewise, from 5.3dB in RCA i/o mode to 11.4dB for balanced in/out to 17.2dB for digital in/XLR out.

Input impedance is 100KΩ on RCA and XLR and the standard 75Ω on coaxial S/PDIF. The headphone socket with its class A TI driver delivers 1.3W into 32Ω, 225mW into 300Ω and 128mW into 600Ω.
the digital board with USB transceiver and clocks in the foreground

From input to output, the mPRE is a dual-mono dual-differential affair. It uses over 80 quad-paralleled Fets for lower noise and increased current and dedicated power supplies per channel. The volume control is a switched resistor array based on the big $2.000 STP-SE preamp. The 24/192 XMOS-based asynchronous USB transceiver naturally requires a driver install for Windows but not Mac.

EJ Sarmento: "Designing a preamp after the bar-setting STP-SE was no easy task as it left some very big shoes to fill. With so many happy STP owners, we found it hard to deviate much even though the mPRE's small form factor required a far more compact circuit. Beginning with the necessity of a dual volume control similar to the STP's based on the very same polysilicone technology also employed in our integrated units—including the mINT—this programmable resistor ladder offers quick and precise level control. It allowed us to utilize the 1-turn knob as an analog reference which is later used to program the volume setting for each isolated channel. To further aid channel separation with these dual volume controls we also implemented dual power supplies to minimize crosstalk. All of these design features help achieve the pure balanced dual-mono analog signal path.

"With so many features derived from our past products, it was only natural to also implement some gravy from the mAMP. This is where the latest FET buffer came in. Following the STP design, we implemented eight unity-gain FET stages to help isolate the volume control from any input/output impedance mismatches in the passive state. Adding another benefit of the mAMP, we decided that its cross-coupled differential stage was a must. Allowing for any combination of connection methods—XLR:XLR, RCA:RCA, XLR:RCA and RCA:XLR—the mPRE remains fully balanced without any additional circuitry or colorations. Most notably listeners will find the mPRE to sound equally good with unbalanced interconnects as it does with balanced cables due to the >82dB common-mode rejection from either.

"We opted to isolate each output with additional FET buffers to eliminate any potential loading or coupling issues. Details such as double switching were added to decrease the typical input bleed-through from -60dB to over -80dB. To keep the signal as pure as possible, further care was taken to ensure that the audio didn't pass through more than a pair of input switches. In addition to the analog inputs, the new µDAC-HD circuit manages all digital sources with ESS and XMOS tech. Whether the need is for high-resolution computer streaming, airport streaming, Redbook playback, a headphone session or just the typical preamp function, the mPRE has the answer. Capable of high drive in excess of 16V balanced in addition to its minimalist approach, the mPRE effortlessly fulfills the needs of many whilst providing exceptional control and conditioning for any source. The mPRE - so simple yet so complicated."

The mPRE's rear panel is once again self-explanatory. 1, on/off switch. 2, IEC power inlet; 3, international voltage selector. 4 - 6, digital inputs. 7, AUX 1 input. 8, AUX 2 input, programmable to HT bypass (eliminates the volume control). 9, balanced inputs. 10, RCA pre-out (variable). 11, RCA pre-out 2 (variable or fixed). 12, balanced output. 13 + 14, selectors for programmable sockets. 15, 12V DC in/out triggers.