Adcom GFP-555II Stereo Preamplifier MM/MC Phono – Made in USA

Adcom GFP-555II Stereo Preamplifier MM/MC Phono – Made in USA

A classic, Made-in-USA high-performance solid-state preamplifier from Adcom’s golden era — the GFP-555II delivers a clean, transparent, wide-bandwidth signal path with an exceptional phono stage, and has been freshly serviced to perform at its very best.

Adcom built its formidable reputation in the late 1980s and early 1990s by offering performance that embarrassed far more expensive competition — and the GFP-555II is the preamp that sat at the heart of countless serious systems during that era. Designed by Nelson Pass associates and sharing its core circuit board architecture with Adcom’s flagship GFP-565 reference preamplifier, the 555II is considerably more sophisticated inside than its modest asking price suggests. An ALPS volume potentiometer, discrete circuit stages, gold-plated connectors, and quality Japanese capacitors and resistors throughout give it a build quality that one reviewer estimated would cost $1,500 to replicate in a new product. The extraordinarily wide frequency response of 5 Hz–85 kHz preserves full signal integrity well beyond the audio band, while a THD of just 0.003% and a line-level signal-to-noise ratio exceeding 100 dB place it firmly in serious high-end territory.

The phono stage is a particular strength — supporting both moving magnet and high-output moving coil cartridges with 90 dB signal-to-noise ratio and appropriate gain and loading. For anyone running a turntable as a primary source, this alone justifies the GFP-555II’s place in a system. Separate listen and record selectors, a processor loop for outboard equipment, tone controls with full bypass, and both main and bypass outputs give the 555II a flexibility that modern minimalist preamps rarely match — you can run a completely direct signal path when desired, or engage the tone controls for fine-tuning without permanently altering the signal chain. A headphone output rounds out a genuinely comprehensive feature set.

The low output impedance ensures the GFP-555II drives virtually any power amplifier or cable length with authority, and it partners particularly well with classic Adcom, Rotel, NAD, and Bryston power amplifiers. This example is in good overall cosmetic condition for its age and has undergone our Level One service and testing which should ensure many more years of reliable performance ahead.

Specifications

Type: Stereo solid-state preamplifier

Frequency response: 5 Hz–85 kHz (line); 5 Hz–60 kHz (phono)

Total harmonic distortion: 0.003% (line); 0.002% (phono)

Input sensitivity: 2.3 mV (MM phono); 200 mV (line)

Signal-to-noise ratio: >100 dB (line); >90 dB (MM phono)

Channel separation: 75 dB (line)

Input impedance: 22 kΩ (line); 47 kΩ (phono)

Output: 2.0 V rated (main); 10 V maximum

Tone controls: Bass ±10 dB; Treble ±9 dB (fully defeatable)

Phono support: MM and high-output MC

Features: Separate source/record selectors, processor loop, tone defeat, main and bypass outputs, headphone output

Country of manufacture: USA

Dimensions: (W x H x D) 17.0 x 3.0 x 11.4 inches / 432 x 76 x 289 mm

Weight: 11.5 lbs / 5.2 kg

A freshly serviced, Made-in-USA classic preamplifier with outstanding phono credentials and genuine high-end circuit topology — the Adcom GFP-555II remains one of the most capable and flexible preamps available at anywhere near its used price point.

Backed by Radique Audio’s 90-day warranty and perpetual trade-back policy, this is a confident, low-risk entry into high-performance separates audio; asking $445.