Wyred 4 Sound SX-500 mono blocks (Excellent)

These behemoths sound stunning. Whether driving very difficult loads or high efficiency speakers, they sound tube like with unforced detail: gorgeous mids and extended but airy, sweet highs. The bass though is staggering. Controlled with an iron fist!
Please read Srajan Ebaen's 6moons review on the stereo version ST500. The SX500 mono blocks significantly exceed the performance of the reviewed ST500 especially in areas of resolution, lower freq control and soundstage depth.
I can cover shipping at asking price. See feedback & buy with confidence. Open to reasonable offers.

Specs from OEM

Typical THD+N 8Ω (10W out): 0.0027%
Power Output 8Ω @ 0.2% THD+N: 250W
Power Output 8Ω @ 1.0% THD+N: 330W
Power Output 4Ω @ 0.2% THD+N: 550W
Power Output 4Ω @ 1.0% THD+N: 625W
IMD (CCIF): 0.0005%
Transient Inter modulation (TIM): 0.003%
Output Idle Noise: <125µV
Efficiency 4Ω: 81% @ 500W
Efficiency 8Ω: 78% @ 200W
Frequency Response 20Hz-20kHz: ± 0.3db
Lower Bandwidth: 3.3Hz (All Loads)
Balanced Input Impedance: 60.4kΩ
Unbalanced Input Impedance: 60.4kΩ
Dynamic Range: 115db
Gain: 27db
Sensitivity: 2.1V
Output Impedance: 0.005Ω
Min Load: 2Ω
Dampening Factor (100Hz 8Ω): 2000
Max Output Current: 35A
Channel Tracking: < ± 0.02 db
Idle Power Consumption: 10W