The DAC on the other hand shows what a difference a few years make. The original model sported a 24bit, 192kHz DAC, but this new board supports DSD 64 and DSD 128 (albeit downmixed to PCM), improves to 32bit PCM precision, and – at present unconfirmed – brings MQA to the Aavik platform. Whether or not these improvements loop back to newer versions of the U-300 remains unclear.
The core of the U-150, however, is functionally identical to the core of the U-300. It’s a 300W Class D design that, like the U-300 before it, doubles its power to 600W into a four ohm load. The arguments about Class D – both positive and negative – have been made time and again. The nay-sayers just see a cheap, cool-running chip amplifier, where the converts see that cheap, cool-running chip amplifier as the starting place to deliver a potentially high-performance sound. It’s all about the implementation, which in some cases means elegant ways to mask Class D operation behind valves or Class A current dumping circuits, and in others means equally elegant ways to extract the best from the chip itself. Aavik chose the latter option.
Back to that ‘volume’ control, which again echoes the U-300 design. Aside from a power-off switch on the rear of the amplifier, the controls are limited to three push buttons on the top plate, and that volume dial. The change here is to the new large LED displays flanking the dial itself. The logic of the trio of buttons has not changed and the button in the middle of the top plate still dims or turns off the display (with such a huge display, this becomes more imporant). As before, but with added readability, the display on the right denotes which input is in use, the one of the left shows volume in 80 steps from –80dB to 0dB. The left button on the top operates mute, but press and hold this button to choose one of three gain settings for an individual source, using the main control knob. The right hand button typically controls navigation (source selection), but press and hold this button and you go into remote control pairing mode. Aavik recommends the standard slim Apple remote to control the U-150. Press and hold both left and right buttons in a three second ‘power chord’ and the amp switches to set-up mode, adjusting the cartridge loading for the optional phono stage, some display management, and the option for a hard reboot.
Where the U-300 looks like a piece of military hardware in its ‘none-more-black’ livery, the U-150 looks and feels more like a modern piece of audio hardware, with styling reminscent of AURALiC and BMC Audio designs. This is no bad thing, as too much deviation from the mean in the looks department might spell reduced sales, but the U-300 had an ace or two up its sleeve. For example, with the U-300’s central barrel, the top buttons were clearly defined. Now they sit on a flatter, more uniform plate. The design changes do help to significantly lower the price of the U-150 however; those D’Agostino like ventilation holes in the side panels of the U-300 were very expensive to make, and the horizontal aluminium heatsink slats are a more expedient option.
What’s great here is the changes between U-300 and U-150 are all based around building a more affordable design without sacrificing the basic circuit. Stripping out subsystems that might be unnecessary for all users, and moving from a more elegant to a more functional and affordable exterior is more than justifiable if the sonics still stand up. And here we get back to the really good stuff.
The amplifier behaves ‘much’ like its bigger brother; if anything, it got to its right operating temperature faster than the U-300 thanks to those horizontal heatsinks. And yes, like its bigger brother, the Aavik runs warm for a Class D design, but not worryingly so. And it also retains that ‘is this thing on?’ noise floor.