post #1 of 1
Thread Starter 
This Classified is Closed

For Sale or Trade:
M3 Stereo Headphone Amplifier With Preamp Function - σ25 Regulated Power Supply - MMM M^3 M Cubed

Will Ship To: United States

I am selling an AMB M³ Stereo Headphone Amplifier with a σ25 Regulated Power Supply. The parts were sourced from AMB and Mouser.


4/5/2014 - Built in the summer of 2012. Put it up for sale a few months later, but couldn't bear to part with it. Now the DIY bug has bitten me again and it is time to build a new amp. Need to sell this before I can justify the expense of a new build. Also have 3 unused AD8610AR OP Amps for rolling that I will throw in for free. Let me know if you have any questions.


As per AMB: "The M³ is a high-end DIY stereo amplifier for dynamic headphones. It includes a number of distinctive features, carefully considered to maximize performance."


I built it myself to the recommended specs on the AMB website with the Bass Boost option. It has two Alps "Blue Velvet" pots for the Volume and Bass Boost controls. It also has Vishay resistors, as well as Nichion and Wima capacitors throughout. It comes with OPA627AP opamps.


I added a pre-amplifier (preamp) function that can be implemented via the toggle switch on the front panel.


As per AMB: "The low-noise performance and moderate voltage gain of the M³ also makes it an excellent line-stage pre-amplifier."


The M3 is built into an aluminum Hammond case that measures 8.66" x 6.3" x 2.1".


It is in perfect working condition, sounds excellent, has no dings or blemishes.


I have listened to the Sennheiser HD 650, ATH-M50, Sony MDR-V6, and Koss Porta Pros. All sound great with this amp.


It comes with an outboard σ25 Regulated Power Supply (110/120V input).


The σ25 is built into an aluminum Hammond case that measures 6.3" x 4.06" x 2.09".


As per AMB: "The recommended configuration for the M³ is to use an outboard power supply. This allows the power transformer and other AC components to be located far away from the sensitive amplification circuitry for minimum induced hum and noise."




- Nichion electrolytic capacitors (low ESR, low impedance, low noise, high ripple current, high temperature, and long life).
- Wima Metal film caps.
- Vishay precision resistors and rectifiers.
- Alps Blue Velvet potentiometers for Volume and Bass Boost.
- Neutrik locking 1/4" headphone jack.
- Gold plated chassis-mount RCA jacks.
- Separate aluminum enclosures for M³ Stereo Headphone Amplifier and σ25 Regulated Power Supply.

- Toroidal power transformer for PSU.

- IEC AC inlet with built in fuse chamber and switch.
- Gold plated DIP sockets.
- Blue chassis-mount LEDs.
- Knurled aluminum knobs.

- Silver plated, Teflon insulated copper hookup wire used throughout.

- Preamp option via toggle switch.

Please see these reviews for additional information and listening impressions.


BONUS: I will throw in an additional unpopulated σ25 regulated power supply printed circuit board.


Serious offers only please. Parts alone cost me $415.00. I have the receipts to prove it and can provide pictures of them if you would like.

$15 shipping via USPS Priority Mail.

I will accept payment via PayPal.

The M3 will ship on the next business day following payment. It will be shipped USPS Priority Mail (2-3 business days).


Please see eBay feedback @ eBay My World - blingblingdr

PM me for high resolution pics of the complete build process.

Edited by BlingBlingDr - 4/5/14 at 3:11pm