From left to right at the back of the subwoofer were an IEC power inlet with fuse and mains switch followed by a pair of speaker terminals for passive mode. Next came XLR connectors, the first two for AES 3 input and AES 3 throughput with another device. To receive a line input signal from an amplifier, there also was an XLR input. A rotary volume knob controls the subwoofer in passive mode or both subwoofer and line array in active mode. An input selector switch determines whether the XLR or RCA input is live. For maintenance and DSP settings—more on that later—one may connect a computer via USB. There are 4 presets with a green LED indicator and mini selector switch. The RCA i/o are followed by two selectors for active or passive mode.To run the system passive, the setting of the top switch should be 'passive' and the input switch below set to 'speaker'. This bypasses the XLR/RCA selector. To run the system fully active, the device selector should be 'active', the input selector at 'line' and either the RCA or XLR line input used. Besides speaker-level and line inputs, the active LA17 also accepts Bluetooth. Only the right subwoofer has a wireless receiver whilst the left loudspeaker must now connect via the RCA output of the right unit.

No active loudspeaker system is without amplification. With our LA17 PA review sample that meant two Hypex UcD400 OEM modules to power the woofers and line array. After June 2019, Audio Alto will transition to Ncore 500. Hypex ship their amplifier modules with DSP soft/firmware. The LA17 uses this DSP for its low/high pass filtering. The subwoofer hands over at 160Hz. When the system runs in passive mode, the curved array presents your own amplifier with a 5Ω load at 91dB efficiency. The phase-linear array again handles the bandwidth of 160Hz to 20kHz +/-2dB.

Though not recommended, one can use the DSP also for room equalization. On-site expert DSP tuning is available within the EU and included in the purchase price as are transportation costs. Settings from the setup session store inside the four options indicated by the green LEDs. A typical option is a setting for listening at (very) low volumes to need just a little extra gain at the extremes. Of course the user can access the DSP options directly by downloading the Hypex HFD software to a Windows PC. Just beware that some settings like the crossover filters are predefined by Audio Alto so shouldn't be overwritten.

We started our listening in passive mode. For that we connected our Audio Note Meishu 300B integrated and selected the settings accordingly. The 91dB efficiency of the fifteen small drivers proved high enough to produce sufficient SPL in our large room. Add to that the active subwoofers handling everything below 160Hz and there were no issues. The Meishu processed digital media from an SGM 2015 and T+A DAC8 streamer/converter source and analog signal from a Holbo Air Bearing Turntable system or a Dr. Feickert Blackbird via our Trafomatic Reference One Phono.

With all connections made and checked, we took another look at the loudspeaker system standing 1.97 tall with the woofer cabinets measuring 48 x 57 x 36cm excluding feet. Those are adjustable to focus the curved line array at the listening position. As Saša  explained, "line arrays are normally used in professional environments like halls and stadiums. The larger distances between speakers and audience minimize problems with acoustic lobing. They must also cover larger surfaces and spaces. My previous line array model was smaller with just 6 drivers in a box. With a smaller number of drivers, the listening position could be closer and the line array flat with minimal lobing."