Pass Labs X600 Monoblocks 600W of Clean Power

General:
The X600 is one of Pass Labs most highly regarded amplifiers, and it's actually still made. I believe they're up to version 8.

Unfortunately at some point they changed the cabinet from this beautiful three dimensional appearance with the big gorgeous round meter to a much more conservative look. I'm partial to these earlier versions.

The circuitry did not evolve much throughout these revisions, and the original X600's are still considered to be an absolutely killer amplifier. 

They're capable of driving just about any load down to 2 ohms, no matter how difficult. It will deliver its power with ease and finesse.

This particular example was well cared for by a single owner. They show no signs of wear, use, or abuse. They were owned by a famous musician which I will share to the new owner.

There are no scratches or dinged corners or any discoloration. That's really something considering their heft. They present extremely nice. 

This X600 set is also an excellent match to the Pass X1 two piece preamp currently available.

These will ship via freight on a pallet for safe transport. Flat rate shipping to the Lower 48 US States is $700. If you're outside of this area please contact us for a quote as we ship worldwide. Local courier also available. 

Technical Notes:
Both amplifiers had their main power indicator LED's replaced as one failed at some point in the past. We carefully set the DC offset and bias for each amplifier as instructed by Pass Labs. Both amplifiers tested to rated power into 8 ohms and passed our in house listening and temperature stability checks.

Ownership:
Single Owner

Connections:
RCA, XLR and Removable IEC Power Socket

General Sound:
Neutral sound with little to no coloration

Cosmetic Condition:
8/10 = Very Good. Excellent front faceplate, one minor flaw on chassis side or top.. See our detailed rating description here.

Working Condition:
Working perfectly and tested in our lab and listening room.

Included:
Unit, manual, and power cord.

Packing:
Will be packed using our highly developed in-house process and custom packing materials.Specs:
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: 600 watts maximum @ 1% THD, 1 kHz, 8 ohms plus, minus 105 volts
Maximum Output Voltage: minus 105 volts
Maximum Output Current: plus, minus 25 amps
Input Impedance: 22 kohm balanced
Damping factor: 60 ref 8 ohms nominal
Slew rate: approx. plus, minus 50 V/uS
Output Noise: approx. 500 uV unweighted 20-20 kHz
Random noise floor: approximately 2 uV
Dynamic range :153 dB (random noise floor to peak output) approx.
Balanced CMRR:  approx. -85 dB @ 1 kHz < 100 mv
DC offset: -85 dB @ 1 kHz < 100 mv
Power Consumption: 600 watts idle, 1800 watts maximum

Dimensions - Each Monoblock Amplifier:
19″ W × 22″ D × 11.5″ H

Weight - Each Monoblock Amplifier:
300 lbs.

Link to Manual:
Click Here

Recommended Cables:

Kimber Kable - RCA Interconnects - Better

Kimber Kable - RCA Interconnects - Best

Kimber Kable - BALANCED XLR Connectors - Better

Kimber Kable - BALANCED XLR Connectors - Best

Kimber Kable - Speaker Cables - Better

Kimber Summit Series Monocle XL Speaker Cables (PAIR) - Best

Kimber Summit Series BiFocal XL Bi-Wire Speaker Cables (PAIR) - Best If Applicable 

Kimber Kable - Power Cords - Better

Kimber Kable - Power Cords - Best

The SkyFi Testing Process for Solid State Amplifiers:

We start with a visual inspection of all internal components to make sure that there are no signs of heat stress or damage. Capacitors are checked for telltale signs of predictive failure including bulging, shrunken wrappers, or physical leakage. We also inspect the PCBs for discoloration from resistors or transistors that may have been running hot. On vintage units we often spot check select capacitors for value and ESR.

If the amplifier passes visual inspection, we move on to a controlled power on sequence using a Sencore safety analyzer to monitor current draw in real time. Once the amplifier is determined to be safe to operate, we connect it to full AC mains for function and power testing. We connect the speaker outputs of the amplifier to a Sencore PA81 Power Analyzer which acts as a dummy load, DC offset monitor, and oscilloscope interface. We start with a low level 1KHz test signal at the amplifier’s input and slowly increase its amplitude while monitoring the output on an oscilloscope for signs of noise, clipping, distortion, or improper channel balance.

We continue increasing the signal level until the amplifier reaches clipping. At this point we take an output power measurement and compare it to the spec sheet of the amplifier to verify proper performance. If the device under test has both balanced and single ended inputs they are both tested at this time. We finish off the bench evaluation with a 1KHz square wave check and a 20Hz to 20KHz sine sweep to assess the amplifier’s frequency response characteristics. This battery of tests will usually reveal if the amplifier has any issues that need further attention.

Before the device leaves the bench, we perform a listening test with actual music using a variety of preferred test tracks. Our benches are outfitted with familiar monitor speakers which help us identify inconsistencies that will not always show up on our test gear. The main things that we are listening for are hum or noise with no signal present, proper center image, clicks, pops, or any other obvious undesirable audio characteristics.

If the unit passes all of these tests it is moved to our long term testing rig where we simulate real word operating conditions for 6-8 hours. This allows us to monitor the unit for signs of thermal runaway or intermittent issues that only crop up when the unit has fully come up to temperature.