"Boasting classic looks and features (e.g. balance, tone, and loudness controls) that hark back to the great designs of the sixties, magnificent build, and absolutely gorgeous sonics, this Japanese import is my kind of integrated amplifier. With a rated 20 wpc of pure Class A power (though in reality delivering considerably more), the L-550A II has more than enough muscle to drive even my low sensitivity Quad  2805s to levels loud enough to satisfy me on almost any music, and the finesse, delicacy and low distortion to make a marriage with these speakers as if ordained in heaven. With its superb tone controls, this is a unit for music lovers as opposed to audiophiles (though for purists, a front-panel button provides straight through operation). "  

 The Absolute Sound June/July 2008  (Reviewed in Issue 177)   Paul Seydor.

Luxman introduced the L-550A and L-590A in 2005, since then we have celebrated our 80th anniversary with commemorative components that have reaffirmed Luxman's status at the pinnacle of high-end audio. In these latest integrated models, the gorgeous texture and three-dimensional performance of our original Class A amplifiers has been retained and further refined. For example, the amplifiers feature a new electronic selector switch, adopted from the input section of the C-1000f control amplifier; the internal circuitry has been revised to include customised OFC wiring and a high-speed Schottky barrier diode has been selected for the power source section; improvements that have notably enhanced the sound quality for greater musical enjoyment.

Chassis bases have superb vibration absorption in order to supress noise levels. The power transformer, electrolytic capacitors and amplifer output stage (see amp block below) are laid out so as not to interefere with each other. To reduce intereference further, the block construction isolates each section using shielding panels, and extensive internal filtering to reject magnetic flux interference. 

Luxman holds many patents for audio engineering, amongst them is the application of  Global Negative Feedback to the output stage, which while widely used throughout the audio industry, they no longer use themselves.
 
Luxman nowadays use a distortion reduction circuit called Only Distortion Negative Feedback (ODNF). This system works by isolating noise & distortion at the output from the music signal and sparingly applying negative feedback to suppress them. Conventional negative feedback systems can have an adverse effect on the music, introducing phase distortion. "The circuit features such an ultra-wide range, ultra- high slew rate and ultra low distortion that it does not use phase compensation for the music signal amplifying circuits." This new technology also ensures that need for a DC servo circuit is alleviated, again improving sound quality.

Both the L-590AII and L-550AII, feature the new high quality electronic selector switch, which is the heart of the C-1000f pre-amp (one of Luxman’s 80th anniversary commemoration models). The sound quality deterioration using the new electronic input switch is now minimal, while channel separation and crosstalk efficiency were raised substantially in comparison with the previous L-550A / L-590A. In addition the illuminated position indicator around the input selector knob, makes it much easier to view the selected position even from afar.

The power supply was beefed up, the L-550A used to consume 160W of electricity, their L-550A II has raised this to 190W; delivering more drive and a firm grip over your loudspeakers.

The L-590AII, L-550AII and the L-509u, feature the new high quality electronic selector switch, which is the heart of the C-1000f pre-amp (one of Luxman’s 80th anniversary commemoration models). The sound quality deterioration using the new electronic input switch is now minimal, while channel separation and crosstalk efficiency were raised substantially in comparison with the previous L-550A / L-590A. In addition the illuminated position indicator around the input selector knob, makes it much easier to view the selected position even from afar.

The integrated amplifiers also benefit from the C1000f in that they use a variation of the LECUA 1000 volume control. At any single volume setting only two resistors are in circuit per channel. The less devices in the signal path, the purer the sound, the cleaner the music.

The amplifier section has not been ignored either; noise and distortion has been kept to a minimum with the introduction of ODNF version 2.2A. The deep, rich Class A tone is available here in Luxman’s entry level Class A integrated amplifier.

Extensive listening was applied to the high purity, oxygen free copper (OFC) cables which are used to transmit the signal throughout the amplifier. These cables have a minimal audible signature and minimal electrical effect on the audio waveform. Linear wide bandwidth frequency response is achieved by the low measured values of both inductance and capacitance. The result, the cables do not color the sound, but pass it through, quickly.

Enjoy the ability to play or record your LP collection with the built-in phono stage which accommodates both Moving Magnet and Moving Coil cartridges. There is also a high quality headphone amplifier, accessible from the front panel. A subsonic filter is also easily accessible on the front panel in order to remove unwanted low frequency noise while you are listening to a record. A mono switch is also available for both loudspeaker setup as well as mono record playback.

Large speaker terminals for driving two individual sets of speakers. At the turn of the speaker switch, it is possible to change between the two pairs of speakers easily. In addition, if the A+B function is used; Takasina capacitors are used to parallel the output which permits bi-wiring a single pair of speakers.

The large-sized power meters, calibrated in decibels are easy to read even from a distance. The logarithmic compression system is easy to grasp and also how this applies to the music. The meters are calibrated from -60dB below full rated power to +3dB above rated power. An 8mm thick acrylic covers the meters, which are normally backlit, though the illumination may be turned off from the remote control.

Easy to use, intelligently laid-out, aluminum remote control; all of the primary functions of the L-590AII and L-550AII, including power on / off can be controlled from the comfort of your listening chair. Besides the electronic volume control, there is also a mute feature. The display meters’ back light can also be turned on / off from the remote control. see below

Tone Controls 

The tone controls might seem like an anachronism in this day and age of minimalism, but they can be remarkably effective in bring to life a less than perfect music collection. We all have music gems in our collection that are sonicly challenging. A lot of the 1980's CDs are quite harsh sounding and the digital glare can be quite fatiguing. Reduce the treble slightly and while the harsh CD is not going to suddenly sound like a reference recording, at least it will now be perfectly listenable. Sit back relax, enjoy the music & forgot about the HiFi. When you want to bypass the tone controls, just engage the Line Straight switch. 

NOTE:          You might also use the Tone Controls for room acoustics’ correction. They are in effect simplified room equalization controls.