Silicon Arts Design ZL120 Monoblock Amplifiers

These are my one-owner Z-120s purchased from Hifi One, a Silicon Arts dealer, at retail. THey are serial number 106001 and106002 which may mean they are the first two of their kind. The obvious advantage to that is the designed would want his first pair out the door to be “perfect”. I used them mostly on the Avant Garde Trios. The Silicon Arts Design ZL 120 monoblocks are incredible solid state amplifiers that bring neutrality to playback and sound like a combination of the best of solid state and tubes.  Designed by Masataka Tsuda of Concert Fidelity fame, this is an incredible opportunity to own world class monoblocks at a fraction of their original $28,000 price tag. These are serial numbers 106001 and 106002, so I’m assuming the first amps in this series. Usually getting early product is a good thing as the designer wants to impress reviewers and dealers so he makes a special effort to get it right.
The ZL-120 is configured as a bridged amplifier whereby the voltage swing is obtained between in-phase and inverted-phase input signals. Following an input buffer stage based a high-performance OpAmp, a phase inverting gain stage provides an inverted high-fidelity copy of the input signal. A Class A driver Stage is used to drive a push-pull output stage consisting of two paralleled pairs of MOSFETs. Great care is taken to calibrate each stage during the assembly. Negative feedback is confined to local gain stages — there is no global feedback. The amplifier's input impedance may be set via a switch on the back panel at either 20 or 100 kOhm to accommodate the needs of both low and high output impedance preamplifiers.
ZL-120 Power Amplifier Type: Monoblock power amplifier
Power Output: 120 wpc @ 8 Ohms
Power Bandwidth: 0.5Hz to 100 kHz (-0.8dB)
Frequency Response: 0.5Hz to 30kHz (±0dB), 0.5Hz to 100KHz (-0.8dB)
THD+N: 5W=0.102%
IMD: 0.1% at rated power, SMPTE 4:1 method
Input Sensitivity: 2V for Rated Power 
Input Impedance: 20kOhm (Low), 100kOhm (High)
Voltage Gain: 20dB
Dimensions: 450 x 150 x 360 (WxHxD in mm)
Net Weight: 48 lbs
Price: $23,000 per pair 
Enjoy the Music’s Dick Osler wrote “There is no doubt in my mind that Masataka Tsuda's designs push the state-of-the-art forward, in both solid-state and vacuum tube design arenas, The end result is fantastic transparency and clarity — a closer approach to the live experience in the home.” Tested for Operation & Sound