Vitus SIA-025 MK II Integrated Amplifier – Ex-Demo

This ex-demonstration Vitus SIA-025 Mk.II represents a rare opportunity to acquire Signature Series integrated amplification at a saving on the new price — a component whose engineering ambition places it among the most accomplished integrated amplifiers in the world, now available from Martins Hi-Fi's Norwich showroom with the full reassurance of our support and ongoing manufacturer backing.

The SIA-025 Mk.II delivers approximately 25W per channel in pure Class A into 8Ω — an operating envelope that covers the vast majority of real-world listening levels with any loudspeaker of reasonable sensitivity — before transitioning seamlessly into Class AB, where it delivers approximately 150W per channel into 8Ω and approximately 300W per channel into 4Ω. This combination of Class A intimacy and Class AB authority defines the SIA-025 Mk.II as one of the most complete integrated amplifiers available at any price, and this ex-demonstration example has been maintained to the exacting standards that Martins Hi-Fi apply to every demonstration piece in the showroom.

The 25% Rule

Every component within the SIA-025 Mk.II operates at no more than 25% of its rated capability under normal conditions — a Vitus Audio engineering discipline applied without exception across every Signature and Masterpiece Series product. This eliminates thermal stress, reduces long-term component degradation, and ensures every element of the circuit operates in its most linear and musically accurate region at all times. The practical consequence is an amplifier of extraordinary longevity — one that will perform at reference level for decades of daily use, and one whose ex-demonstration status represents no compromise whatsoever to its long-term musical authority.

Fully Balanced Architecture

The SIA-025 Mk.II is fully balanced throughout — three XLR balanced inputs and two RCA single-ended inputs, balanced speaker outputs, and a signal-to-noise ratio exceeding 100dB that renders the noise floor effectively inaudible. A preamplifier output via XLR allows the SIA-025 Mk.II to be used in a bi-amplification configuration with a dedicated power amplifier such as the Vitus SS-025 Stereo Power Amplifier, extending the system's dynamic authority without sacrificing the integrity of the SIA-025 Mk.II's preamplifier section. The fully balanced architecture delivers a common-mode noise rejection that allows low-level detail and fine spatial information to emerge with a precision and naturalness that single-ended designs cannot replicate.

Full Bypass Function

The SIA-025 Mk.II incorporates a full bypass function for complete compatibility with external surround processors — allowing it to serve as the high-quality stereo amplification foundation of a wider AV installation while retaining its full two-channel musical authority without compromise.

Relay-Controlled Volume

Volume is controlled via a relay-controlled fixed resistor network, operating across -81dB to +11dB in precise 1dB steps — eliminating the tracking errors and channel imbalance of conventional potentiometers, and preserving the SIA-025 Mk.II's extraordinary low-level resolution at every point on the volume range.

Technical Specifications

Who Is It For?

This ex-demonstration SIA-025 Mk.II is for the listener who wants the full authority of Vitus Audio Signature Series amplification at a saving on the new price — who values Class A operation at realistic listening levels, full bypass and bi-amplification flexibility, and the practical elegance of a one-box solution that sacrifices nothing musically. It partners naturally with the Vitus SD 025 MK2 as a digital source of equivalent Signature Series ambition, and with the Vitus SP-103 Phonostage for those whose primary source is vinyl. For those weighing the SIA-025 Mk.II against the next step in Vitus Audio integrated amplifier design, the Vitus SIA-030 makes a compelling comparison at our Norwich showroom.

Buying from Martins Hi-Fi

Martins Hi-Fi has been in Norwich since 1968. Elizabeth Gould runs the business today, and we stock only brands we have heard properly and stand behind. This ex-demonstration SIA-025 Mk.II has been used in our Norwich showroom and is available to hear in the context of a complete Vitus Audio Signature Series system — speak to Dave or Chris, who can demonstrate it with partnering sources and loudspeakers, and advise on system matching and configuration. An opportunity of this quality will not remain available indefinitely.

Contact us at info@martinshifi.co.uk, call 01603 627010, or WhatsApp on 07554 687137. You can read more about how we work on our Why Martins Hi-Fi page. We are at 85–91 Ber Street, Norwich, NR1 3EY.