Since the review sample we received included both optional modules, the DAC-1 and the Phono-1, the Tune Six effectively replaced our entire reference system, with the exception of the loudspeakers (ATC SCM-50PSL), which it was tasked with driving. We evaluated the phono preamplifier using our familiar Linn Sondek LP12/Ittok/Karma combination, while the optical digital input was fed by the WiiM Pro, allowing us to assess the performance of both additional circuits. Most of the listening evaluation, however, was carried out through the built-in streamer, connected to the local network via Ethernet.
Setting up the Tune Six is straightforward. It is a large and fairly heavy component, so it needs to be placed on a stable surface with sufficient clearance for ventilation. The large, easy-to-read display makes operating the unit a pleasant experience, but most of the adjustments are likely to be made through the WebUI, which is particularly helpful when configuring the phono stage if you want to explore its settings in some detail. Call me old-fashioned, but once everything was installed and configured, I used the conventional remote control to adjust the volume and select inputs. It has a good feel to it.

The first impression you get when listening to the Tune Six is that of an amplifier with very good drive capabilities. Our reference loudspeakers behaved much as they do when driven by powerful amplifiers: they reached high levels effortlessly, with no trace of compression, while consistently retaining a smooth, gentle character and showing no signs of harshness. Add to this a disciplined, clearly defined presentation and the tonal balance you would expect at this price level, and you have the hARt Lab integrated amplifier in a nutshell. It is essentially a combination of the company’s basic preamplifier and power amplifier in a single chassis, designed to preserve the fundamental idea behind both: a tube-based sonic character combined with the drive capabilities of solid-state output devices.

Looking at the details, the amplifier reached deep into the low frequencies with ease, demonstrating a substantial ability to reproduce bass weight and impact, while creating imposing sonic images and a strong sense of presence in the room. It is clear that it will feel at home driving a loudspeaker of average or typical sensitivity, even in a large room and from reasonable listening distances. Electronic instruments, the pipe organ and large string sections took shape and unfolded their tonal colors effortlessly, with plenty of dynamic headroom.
Building on this foundation, the amplifier also revealed its excellent capabilities in the bass region. Impeccable reproduction of weight, a commanding dynamic presence, and rhythmic passages with a satisfying sense of body, without any tendency towards excess, combine to produce bass that moves the listener emotionally—and sometimes physically, in the form of foot-tapping. It draws you into the music, demonstrating an excellent ability to portray the low frequencies with ease and without unnecessary exaggeration. The impression created by this behavior is that the amplifier can drive just about anything without breaking a sweat. It is a psychoacoustic trick, a rabbit pulled out of hARt’s hat: the company manages to conceal the limits—which certainly exist—behind a judicious tube character that is very easy on the listener’s ears.
This approach reaches its peak in the reproduction of the midrange. The presentation is not conventionally relaxed, gentle, soft and, ultimately, euphonic. Instead, it is quite detailed, transparent and free of compression, with an excellent sense of layering in complex works containing substantial energy in this region. The amplifier does not seem to impose any recognizably tube-like character on the final result. The midrange is reproduced with a very good feeling of luminance, at the right distance from the listener, never becoming oppressive and without sacrificing presence. Voices were rendered with good balance and convincing positioning and movement, whether we were listening to a soloist or a large choir. If one were to assign the Six a distinctive character in this respect, it would be a tendency towards a gentle presentation, particularly during soloists’ climaxes, which makes the result attractive and enjoyable.
At the top end, the Tune Six demonstrated ample extension, good timing and a fast, transparent presentation. The tonal balance leans towards the smooth side, with good, slightly rounded reproduction of sibilants, and rich harmonics. The result remains lively and fast, with a convincing metallic quality, but without excessive warmth.
The amplifier’s ability to convey musical detail also depends, of course, on its capacity to produce a high-quality stereo image. There is clarity and discipline in the presentation of dimensions, a good sense of depth, excellent focus of individual sonic objects, and convincing portrayal of movement. Everything is in its proper place, while the amplifier’s very low noise floor provides a dark background against which the dynamic contrasts and the dynamic profile of each recording can emerge clearly.

The performance of the streamer through the DAC-1 module leaves little room for surprises when the Tune Six is asked to play through its optical digital input. All the qualities described above remained intact when we switched to the WiiM Pro, and the result was exactly what we expected: the amplifier’s character did not change at all. The identity of the digital source is not what determines the final result; it is clear that the combination of the tube-based preamplifier stage and the MOSFET output stage plays the dominant role.
As for the second optional module, the Phono-1 comfortably rises to the occasion, matching the overall standard of the amplifier. Configuration is straightforward through the menu and WebUI, and it offers exactly what vinyl enthusiasts would want: low noise and accurate RIAA equalization, allowing the final result to remain transparent while preserving the character of the analogue front end as the signal passes directly to the following stages, making the most of every record groove. Good bass weight and rhythm, together with excellent imaging and high-frequency extension, are its defining characteristics. It would be a good idea to see hARt offer it as a standalone component at some point.

Conclusion

To sum it up, the Tune Six is exactly what hARt intended it to be: a scaled-down version of its smaller preamplifier/power amplifier combination (Tune Two/Tune Three), housed in a single chassis, with a more modern and user-friendly interface, at a more accessible price. It is a turnkey solution that, nevertheless, remains true to the company’s fundamental ideas and values. This is undoubtedly a major success, because the compromises are genuinely negligible and the finished product is excellent, both as a concept and in terms of sound quality. Personally, I believe this is an exceptionally interesting take on the integrated amplifier. If you are shopping in this price category, you should definitely take a closer look and give it a listen!

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