During the listening sessions, Tune Three replaced the reference power amplifier (Parasound HCA3500) and undertook to drive the usual reference loudspeakers (ATC SCM-50PSL). The rest of the system was the standard chain we use at avmentor, including the Teac Esoteric P70/D70 transport/DAC pair, a dCS Puccini U-Clock, and the Melos Plus Series Line preamplifier.
The initial setup is quite easy. The only things needed are a sturdy surface and enough space around the device, for proper ventilation, both reasonable for a power amp of this size and power, which, also, includes a tube stage.
The first impressions you get by listening to the system with Tune Three as the power amplifier, are those of very good dynamic contrast and some serious sound level capacity. The SCM-50s were driven comfortably, without any trace of fatigue, and the amp seemed to have the potential to handle a medium sensitivity in high sound levels, without any difficulty. This attribute is, perhaps, the essence of hARt's ideas, as the system never appeared hard, rough, or annoying, always remaining on the soft, pleasant, and bright side of things. This behavior could be probably attributed to the tube-based part of the amplifier. Essentially, it is mainly the VAS sound that the listener is exposed to, and, given this fact, we can consider that the company achieves exactly what they want: to create an amplifier with some serious driving capacity that possesses the good sound attributes of a tube circuit!

To the details, towards the very low-frequency part of the audio spectrum, the system was clear, and fast, with very good transient and detail descriptions, offering a good feeling of volume. Compared to the reference amp, it appeared airier, and mild-sounding, filling the listening space comfortably and -given the proper recording- creating an imposing sound field effortlessly.
This behavior extends to the rest of the low-frequency band, the result being a clear, fast, and well-scaled bass line, with a good sense of discipline and timing features. The rhythm section appeared with a good sense of fullness, strong presence, and without any unnecessary emphasis, especially towards the upper-bass band, giving a sense of neutrality and balance. Music works with large string instruments or with rich electronic sounds, were rendered with a sense of proper balance and very good presence. In general, the whole low-frequency band was characterized by the pleasant impression that everything flows correctly and well-controlled.
The mid-band is one of the amplifier's strong points and - probably - the source of its sound identity. Here, we have a balanced sense of vivacity, combined with an enjoyable, almost tangible, performance with the system reproducing even the most complex components in a way expected from a truly great amp.
Without notable concessions to accuracy and tonal balance, listening remained relaxed and amiable, even for sound levels outside what you would call "advisable" for your space and distance from the loudspeakers. The result sounds natural, with a very good dynamic contrast and a particularly dark background, an attribute surfacing during any low music passage and exacerbating the sense of "being there".
Voice works, solos, and choir-based, of small and large scale, were sensational, with an excellent feeling of air, and accurate description of group position and movement. As you would expect from an amplifier at this level, there are no traces of bias towards a specific program type. Tune Three feels as comfortable playing back small groups and large orchestras without the slightest sign of any difficulty.
Stereo imaging of the system with the Tune Three has maintained the very high-quality level I am used to by the ATCs and the Teac Esoteric pair but appeared to be noticeably better, offering a more disciplined description of the horizontal axis with a very clear focus, feeling of depth and better air between the discrete sound sources. The system manifested an excellent capacity in the mix details description, with better clarity, presence, and transparency, all maintained even at very high sound levels.
Towards the higher part of the spectrum, the system offered a very good sense of extension and equally good transient features. Percussive instruments, heavy in high-frequency components, appeared well bodied with impeccable decay/release timing, with a somewhat leisurely attack description, compared to the reference, but with very good harmonics and a well-balanced feeling of warmth. Having said that, it is important to emphasize that the amplifier seems to completely lack any of the tube-inspired melodrama, a not uncommon trait in some tube designs, as it is, perhaps, unnecessary to mention that both roughness and dryness are completely absent. The result is a well-balanced, delectable -almost groovy- and accurate high-frequency rendering.

Conclusion

In conclusion, Tune Three proved to be a somewhat perplexing device to review, mainly because it is difficult to understand what the amp does and how it does it, after first realizing that it is, really, a different approach in comparison with what we recognize as "standard". hARt Lab's idea for a power amp that embraces the positive values of the tube-based circuits but the driving capacity of a MOSFET-based output stage seems to work as the company intends, clearly better than some other, rather timid, hybrid designs which seem "ashamed" for using tubes. By maintaining a mild, progressive behavior at high sound levels and -at the same time- showing some serious power potential, it is, indeed, an ideal choice if you want to drive a difficult loudspeaker without feeling that you are oppressed by a beastly semiconductor-based power stage. Tune Three is a good idea with impeccable implementation and offers a great first impression for a newcomer. Well done!

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