721

About the 721

The Soulution 721 stereo preamplifier offers three unbalanced RCA inputs and one balanced XLR input, with one balanced and one unbalanced output. It features a maximum output voltage of 16 Vrms balanced and 8 Vrms unbalanced, with a low output impedance of 2 Ohms. The preamplifier operates with a frequency response from 1 Hz to 1 MHz (-3 dB) and a total harmonic distortion (THD) of 0.0006%, ensuring extremely clean and detailed sound. It uses a unique volume control system combining a high-precision resistor network switched by reed relays and a secondary programmable gain amplifier active only during volume changes to eliminate switching noise. The output stage runs in Class-A with a 40mA idle current, optimized for velocity, precision, and impulse current rating, and is stable on all loads including long cables. The 721 has two separate power supplies for audio and digital circuits with multi-stage filtering to minimize interference. The chassis is made of black/silver anodized aluminum, measuring 480 x 167 x 450 mm and weighing 30 kg. It includes remote turn-on via 12V link signal and adjustable display brightness. The preamplifier is designed for ultra-high fidelity with a spatially three-dimensional and holographic soundstage reproduction. It is no longer in current production but remains highly regarded in audiophile circles.