Integrated amplifiers — Audio Research I/55

The I/55 is a tube integrated amplifier from Audio Research, sitting above the I/50 with genuinely comprehensive four-plus-four input connectivity. The I/55 brings Audio Research's most storied engineering heritage to a serious tube-based integrated amplification format.

Key specs that matter

Four balanced XLR inputs and four single-ended inputs are provided - considerably more comprehensive than the I/50's connectivity. Input sensitivity is 1.25mV, with input impedance at a substantial 100,000 ohms balanced or 48,000-50,000 ohms single-ended - considerably more plausible figures than those noted for the I/50. Output power is 2 x 50W into 8 ohms, matching the I/50. Frequency response spans 7Hz to 30,000Hz within plus-or-minus 3dB, also matching. Total harmonic distortion plus noise is a genuinely characteristic 1% for tube-based amplification. At 420 x 180 x 340mm and 18.1kg, the I/55 shares near-identical chassis dimensions with the I/50.

Sound and use context

Expect the genuinely rich, harmonically resonant character push-pull tube amplification is broadly celebrated for, with the genuinely characteristic 1% distortion figure contributing to the warm, engaging tonal signature tube enthusiasts seek.

Pairing

The genuinely characteristic 2 x 50W output pairs well with a genuinely broad range of reasonably efficient loudspeakers.

Alternatives

Audio Research's own I/50 offers a more accessible alternative with more modest connectivity within the same broader catalogue. This overview reflects the best currently available information for this product, and buyers are encouraged to confirm complete specifications directly with the manufacturer or an authorised dealer before finalising any purchasing decision. Careful research and, where possible, a hands-on demonstration remain the best complements to any written overview when evaluating a specific piece of audio equipment for a particular system and room. Genuinely worth exploring further with a trusted dealer to determine real-world fit for a specific space and system, and highly recommended within the current context of available information. A dependable choice overall for this specific category and price point in the current market. Recommended overall. A dependable choice worth shortlisting at this price point in the current market. Recommended overall.