Drop O2 Headphone Amplifier

Baseline Perfect

In 2011, audio engineer NwAvGuy published a blog post titled “O2 Headphone Amp,” in which he outlined his philosophy on defining sound quality and detailed his ideal audiophile circuit design. Our version of NwAvGuy's famous O2 amplifier, the Objective 2 Desktop Edition features updates based on feedback from the community. It’s an ideal baseline reference amplifier, capable of powering everything from IEMs to HD 800s with linear ease. 

Note: This product is available in 120-volt and 220-volt variations. Please confirm the voltage your country uses before placing your order. If you’re unsure of your country’s voltage, use this list.

Drop O2 Headphone Amplifier
Drop O2 Headphone Amplifier
Drop O2 Headphone Amplifier

Community-Driven Design

The O2 was made for benchmark performance at an entry-level price, something the audiophile world had never seen before. But while NwAvGuy was satisfied with purist input, output, and power arrangements, the Drop community wanted more options. Following the initial launch of the Objective O2, the discussion lit up with more than 500 requests for changes to the input, output, and power configuration. Members asked for a quarter-inch headphone output, RCA inputs, and a rear-mounted power jack, and we were happy to oblige. Thus, the Desktop Edition was born.

Drop O2 Headphone Amplifier
Drop O2 Headphone Amplifier

Standard Gain vs. Medium Gain

We recommend the medium gain version if you plan to primarily use this amp with IEMs. If you don't plan to use IEMs, if your headphone has a 300-ohm or higher impedance, or if your source is weak (less than 2V output), opt for the standard gain version to ensure enough power.

Drop O2 Headphone Amplifier


  • Input: RCA 
  • Output: 6.35 mm 
  • Power: Battery (not included) or AC adapter (included, select 120V or 240V)
  • Gain: 2.5x and 6.5x / 1.0x and 3.3x (select your configuration)
  • Volume potentiometer taper: Alps 15A or 3B
  • Frequency response: +/-0.1 dB (20 Hz–20 kHz)
  • THD at 1 kHz, 150 ohms: 0.0016%
  • IMD CCIF at 15 ohms: 0.001%
  • IMD SMPTE: 0.002%
  • Noise (ref 400 mV): -105 dB
  • Max output (33 ohms): 613 mW
  • Max output (150 ohms): 355 mW
  • Max output (600 ohms): 88 mW
  • Output impedance: 0.54 ohms
  • Crosstalk (15 ohms): -65 dB
  • Channel balance (50% volume): 0.6 dB
  • Case dimensions: 4.12 x 3.87 x 1.12 in (10.46 x 9.82 x 2.85 cm)
  • Weight: 9 oz (255 g)


  • 120V or 240V AC adapter (add plug adapter for your country’s outlet)


We get it. Sometimes what you ordered just doesn’t work out. If that’s the case for you, don’t fret! All customers (both US and international) may return or exchange this item in new, unused condition within 30 days of delivery.


Domestic (contiguous US) customers will have a choice of shipping options at checkout. The shipping days / arrive by date displayed represent the transit times from the estimated ship date for your order to be delivered.

Estimated ship date is Oct 21, 2021 PT.

Payment will be collected at checkout.

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