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Adcom GFA-555se Stereo Power Amplifier
$1,899.00
Product Details
ADCOM GFA-555se Power Amplifier
Legacy
GFA-555se power amplifier represents the pinnacle of ADCOM’s audio engineering. This Nelson Pass design broke ground when it came out in the 80’s, getting rave reviews and providing tank-like reliability at a decent price. That these audio power amplifiers are still much in demand after so much time is a strong testament to their value and durability.
Better Sound Delivery
Adcom GFA-555se Stereo Power Amplifier
A legend — refined for a new generation.
The Adcom GFA-555se carries forward the legacy of one of the most iconic amplifiers in hi-fi history, reengineered for greater transparency, control, and musical refinement. Designed to deliver effortless power with precision, it brings a sense of scale and authority that transforms any listening experience.
Producing 200 watts per channel into 8 ohms and 300 watts into 4 ohms, the GFA-555se offers substantial headroom and the ability to drive even the most demanding speakers with confidence. Its high-current design ensures stability and control, maintaining clarity and composure across the entire frequency range.
What sets the 555se apart is its balance of strength and subtlety. Bass is deep and commanding, the midrange is open and expressive, and the highs extend with a smooth, natural ease. The result is a presentation that feels both powerful and refined — capable of revealing detail without ever sounding forced.
With upgraded internal components, balanced XLR inputs, and a modernized circuit design, the GFA-555se builds on its heritage while elevating performance to meet contemporary high-fidelity expectations.
Key Features
- 200W per channel (8 ohms) / 300W per channel (4 ohms) — authoritative headroom for any speaker
- Bridgeable to 600W mono (8 ohms) — maximum power for single-channel or subwoofer applications
- Damping factor ≥900 (20Hz–20kHz) — exceptional speaker control and bass precision
- Balanced (XLR) and unbalanced (RCA) inputs — flexible integration with any preamplifier
- Ultra-wide power bandwidth — 1.7Hz to 100kHz (−3dB)
- Dual voltage compatible — 120VAC & 230VAC / 50–60Hz for worldwide use
- Upgraded internals — modernized circuit design with enhanced clarity and refinement
- Robust build quality — classic Adcom reliability, built to last
Technical Specifications
| Specification | Value |
|---|---|
| Output Power – 8 Ohms (Stereo) | 200W per channel |
| Output Power – 4 Ohms (Stereo) | 300W per channel |
| Bridged Mono Power – 8 Ohms | 600W |
| Frequency Response | 10Hz – 20kHz, +0 / −0.25dB (1W into 8 ohms) |
| Power Bandwidth (−3dB) | 1.7Hz – 100kHz |
| Input Impedance – Unbalanced (RCA) | 100k ohms |
| Input Impedance – Balanced (XLR) | 10k ohms |
| Input Sensitivity | 1.75V rms (200W into 8 ohms) / 130mV rms (1W into 8 ohms) |
| Damping Factor | ≥900 (20Hz – 20kHz) |
| Power | 120VAC & 230VAC / 50–60Hz |
| Maximum Dimensions (H × W × D) | 7½' × 12½' × 17' (191 × 318 × 432 mm) |
| Weight | 36 lbs. (16.3 kg) |
| Shipping Weight | 39 lbs. (18 kg) |
Frequently Asked Questions
What is the Adcom GFA-555se?
The Adcom GFA-555se is a stereo power amplifier from Adcom, USA, delivering 200 watts per channel into 8 ohms and 300 watts per channel into 4 ohms, with a damping factor of 900 or greater and a power bandwidth of 1.7Hz to 100kHz. It is the modernized evolution of the original Nelson Pass-designed GFA-555, featuring upgraded internal components for lower distortion (0.003%), higher signal-to-noise ratio (110dB+), and balanced XLR inputs alongside unbalanced RCA. The GFA-555se is available at Vinyl Sound in Buffalo, NY as an authorized Adcom dealer.
How does the Adcom GFA-555se compare to the NAD C 298, Emotiva XPA-2 Gen3, and Parasound Halo A 23+?
The GFA-555se occupies a distinct position among these competitors. The NAD C 298 uses a Purifi Eigentakt Class D module rated at 185W into 8 ohms, offering exceptional measured noise performance and efficiency in a lighter chassis, but operates on a fundamentally different topology than the GFA-555se's traditional linear high-current Class A/B design. The Emotiva XPA-2 Gen3 delivers 300W into 8 ohms at a similar price but with a lower damping factor and no balanced input stage as refined as the GFA-555se's differential XLR circuit. The Parasound Halo A 23+ offers 160W into 8 ohms in a high-bias Class A/B design with a strong reputation for midrange finesse, but at notably higher cost and lower output power. For Buffalo and Western New York buyers who want proven high-current authority rooted in a legendary design lineage, Vinyl Sound carries the GFA-555se for in-person evaluation.
Who originally designed the Adcom GFA-555 and why does it matter?
The original GFA-555 was designed by Nelson Pass, who is widely considered one of the most significant amplifier engineers in hi-fi history and who later founded Pass Laboratories. Pass brought to the GFA-555 the same high-current, direct-coupled, low-feedback circuit philosophy that defines his own amplifier designs — resulting in an amplifier that, at its price, offered a soundstage stability and dynamic openness that had previously cost many times more. The GFA-555se preserves that foundational architecture while adding updated components and certifications, making it a direct continuation of one of the most respected engineering lineages in the amplifier category.
What improvements does the GFA-555se make over the original GFA-555?
The GFA-555se achieves substantially lower distortion than the original — 0.003% versus approximately 0.04% — and raises the signal-to-noise ratio from around 101.5dB at 1 watt to over 110dB at full 200-watt output. All internal circuitry has been updated to meet current ETL/ETLc, FCC, LVD, and CE/EMC certification standards, using UL-approved FR-4 printed circuit boards and ultra-low ESR electrolytic capacitors throughout. The GFA-555se also adds balanced XLR inputs, which the original did not offer, along with dual voltage compatibility for international use. The chassis footprint and front panel styling remain true to the original design.
Can the Adcom GFA-555se drive difficult or low-sensitivity loudspeakers?
Yes. The GFA-555se was designed specifically for the high-current demands of difficult loudspeaker loads, and its damping factor exceeding 900 provides exceptional control over reactive and low-impedance speaker systems. It is a particularly well-documented match for planar-magnetic speakers such as Magnepan LRS and similar designs, where high current delivery and a low output impedance are essential for stable, full-range performance. The amplifier delivers its full rated power into 4-ohm loads as well as 8-ohm loads, with both channels driven simultaneously.
Does the Adcom GFA-555se support bridged mono operation?
Yes. The GFA-555se is bridgeable to mono, delivering 600 watts into 8 ohms in that configuration. Bridged mono mode is well suited to driving a high-excursion subwoofer, a large center channel loudspeaker, or any single-channel application requiring maximum output from a single chassis. A rear-panel selector switch enables bridged operation; consulting the included instruction manual before switching modes is recommended, as the unit's default switch position should be verified prior to first use.
Where can I buy the Adcom GFA-555se in Buffalo or Western New York?
The Adcom GFA-555se is available at Vinyl Sound, an authorized Adcom dealer located in Buffalo, NY. Vinyl Sound serves audiophiles across the Buffalo metro area and greater Western New York with expert guidance on amplifier selection, speaker pairing, and system setup. Visit vinylsound.com or stop in to hear the GFA-555se in person.
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