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Bryston 2.5B³ Cubed Balanced Stereo/Dual-Mono Power Amplifier

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Pickup currently unavailable at SkyFi 479

Bryston 2.5B³ Cubed Balanced Stereo/Dual-Mono Power Amplifier

Bryston 2.5B³ Cubed Balanced Stereo/Dual-Mono Power Amplifier

SkyFi 479

Pickup currently unavailable

479 South Broad Street
Glen Rock NJ 07452
United States


Super clean and capable amp from Bryston.

Working like the day it left the factory and showing only slight signs of use.

MSRP $5000

We also ordered a factory fresh original 2.5B³ box from Bryston which just arrived and is included your purchase.

Click below to add our recommended matching cables from Kimber Kable, all brand new as SkyFi is an official Kimber dealer.

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

More from Bryston:
For some, it's a gateway drug. The 2.5B³ is the least expensive way to get a Cubed Series amplifier, but it's far from cheap. Made with the same materials and loving care in our Peterborough, Ontario factory as every other product we make, the 2.5B³ will still surprise you with it's startling dynamics, crystal clarity and 3D enveloping spaciousness. You've really got to hear one to appreciate what an incredible deal this model is.

From "The Audiophiliac" himself Steve Guttenberg:
"The sound of the entire band was palpably realistic, the 2.5B3 stayed out of the way and let the music shine."

• Balanced XLR and Single ended RCA input
• 2 Channels each with fully independent power supplies including transformers
• 135W into 8 ohms (and up to 180 into 4 ohms) per channel
• The patented Salomie circuit found in all Cubed Series amplifiers
• Switchable gain (23dB or 29dB)
• Fully convection cooled means no noisy fans
• Machined and anodized aluminum enclosure and dress panel
• Less than 500mW standby power consumption
• SoftStart microprocessor controlled startup sequence won't trip circuit breakers
• DC trigger for automated turn on and turn off
• Legendary Bryston 20 Year Warranty

Inches: 17" W x 4.5" H x 14.75" D

28 lbs

Frequency Response:
<1hz - 100khz: -3db

THD+N (20Hz-20kHz @ Rated Power, 8Ω):

Power Output (per channel):
135W @ 8Ω | 180W @ 4Ω

RCA: -<106db
XLR: <-111db

Input Impedance:
Unbalanced 30kΩ
Balanced 30kΩ+ / 6kΩ-

Bryston 2.5B³  Cubed Balanced Stereo/Dual-Mono Power Amplifier - Manual

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.



Bryston Box

Yes & New


Not Included


Not Applicable


Yes Included

Physical Condition (Info Here)

7 / 10

Working Condition

10 / 10

SKU: 103703