Pass Labs X250 Stereo Reference Amplifier
Despite the powered speaker trend in professional studios, it is reassuring that separate amps like the Pass X250, when combined with state-of-the-art speakers, continue to set the standard for premier amplification when cost is not a limiting factor. Yeah, its $6,000 and not for every studio’s budget. But if you are into listening to the intricate subtleties of recording and mastering, the Pass Labs X250 is an A-list amp.
All of this comes at a high price, but Pass has never been anything but a high performance manufacturer. The power supply is the most expensive part of an amplifier, and the power supply in the X250 is massive, having a 1.2 kVA toroidal transformer, and twenty 10,000 µF capacitors with ± 47 Volts, which provides 221 Joules of energy storage. That is why it doubles its output power from 250 watts into 8 Ohms to 500 watts into 4 Ohms. And, this is with some bias into Class A (the power consumption at idle is 270 watts, which suggests about 25 watts of Class A for each channel).
All figures obtained after 1 hour warmup, with regulated 120 VAC power line. See manual
notes about AC power line regulation.
Gain 30 dB
Freq. Response 0 dB at DC, -3 dB at 100 kHz
Power Output 250 watts maximum @ 1% THD, 1 kHz, 8 ohms
Maximum Output Voltage plus, minus 65 volts
Maximum Output Current plus, minus 20 amps
Input Impedance 22 kohm balanced, 11 kohm unbalanced
Damping factor 250 ref 8 ohms nominal
Slew rate approx. plus, minus 50 V/uS
Output Noise approx. 300 uV unweighted 20-20 kHz
Random noise floor approximately 2 uV
Dynamic range 148 dB (random noise floor to peak output)
Balanced CMRR approx. -85 dB@ 1 kHz
DC offset < 100 mv
Power Consumption 270 watts idle, 1200 watts maximum
Dimensions 19 ” W x 22″ D x 9.5″ H
Shipping Weight 110 lbs.