HiFi-Plus 66: Luxman L-550A-II Integrated Amplifier

Save for a brief period at the end of the last century, Luxman has been producing a distinctive range of high end audio equipment since 1925. Re-launched in 2005, the current range includes both vacuum tube and sold state amplifiers and a range of CD, SACD and universal disc players. The L-550A-II here is the entry level Class A integrated amp with another integrated and a range of pre-power amps above it. The L-550A-II is a descendent of the original L-55 Class A amp of 1981 and shares much of the same design philosophy whilst at the same time benefitting from nearly thirty years of technological advancement.

Arriving well packed in a truly enormous triple-thickness box, the L-550A-II is nothing if not imposing. The overall dimensions are more in keeping with an AV receiver and it is likely that the top shelf of an equipment rack will be required to accommodate it. Fit and finish is extremely good – the casework is non resonant and the major controls operate with a precision and solidity that is reassuring considering the number of them on the front panel. Unusually in this day and age, the L-550A-II has front panel controls, for bass, treble, balance, recording input selection, speaker selection and a stereo/mono function. In addition there are push button switches for additional functions- including of course a button to switch most of these functions out of the circuit. The large input selector control and volume knob flank a pair of backlit VU meters that help to give the L-550A-II an unashamedly retro appearance. Special mention must be given to the remote which is a rather lovely affair comprising a one piece wraparound aluminium top section with well spaced and clearly marked buttons that control volume, input selection, stand by and muting. I can also hopefully save a would be owner a few minutes of head scratching by pointing out there is a master power switch on the underside of the unit. I am sure this is mentioned in the manual but as the entire document is in Japanese, it is not entirely obvious for us gaijin.

The rear panel has four line inputs, a switchable moving magnet/moving coil phono stage and two tape loops. Two of the line inputs can be selected to run via balanced inputs, a function that is increasingly useful as this connection becomes increasingly common on source equipment at the price. An interesting feature of the balanced inputs is that both wiring types of XLR connector are accepted as the earth can be switched by pushing a small button next to the input. This is welcome as the L-550A-II will work happily with any balanced unit irrespective of its origin. A linked set of connections allow the L-550A-II to operate as either a pre or power amplifier. Out of the box, all the connections are covered with blanking plugs which if nothing else help to keep the connections dust and dirt free.

Internally, the L-550A-II is as well constructed as its exterior suggests with a well laid out circuit and good quality components throughout. The lower plate of the chassis and the four feet on which it sits are heavily damped and suggest that considerable effort has been taken to make the amp as inert as possible from the ground up. Stated output is 20 watts into 8 ohms rising to 30 watts into 4 ohms at commendably low distortion figures. The output is split over two sets of speaker terminals that can be switched in and out independently. The L-550A-II makes use of a proprietary Luxman circuit described as Only Distortion Negative Feedback (ODNF) which works to identify distortion and noise and apply only sparing levels of feedback to suppress them. Also present is a line phase sensor, a device that can ascertain if the mains outlet is incorrectly wired. I am pleased to say that the sensor indicated that all was fine with my mains, which is perhaps just as well as I would not have had the faintest idea on how to correct the situation if it wasn’t.

Sonically the Luxman is a talented and in some ways surprising amplifier. First and most obvious is that the 20 watt output seems to go an awfully long way. Partnered with my B&W’s which although not insensitive do respond well to a healthy power input, it generated more than adequate levels for my listening environment. Elaborate preparations I had made to do much of the critical listening through a pair of Living Voice OBX’s proved fairly irrelevant although one extended session was carried out with them revealing that results with larger, more sensitive speakers were no less impressive. At no stage did the L-550A-II suggest that it was anywhere near running out of steam. The output from unbalanced inputs, balanced inputs and the phono stage were all surprisingly close and all could achieve levels that were more than adequate. Like other Class A designs, the L550A-II takes a little while to reach its working temperature and optimal performance but this is only a matter of minutes and although warm, the top plate is safe to touch at all times. The overall presentation is reasonably neutral with slight warmth to the upper registers giving lushness to vocals I found extremely appealing. It is extremely accurate with piano, strings and other instrumental tripwires sounding tangibly real and possessed of a genuine presence. This tonality and detail is achieved without falling into stridency and harshness which is a welcome achievement. A convincing soundstage is generated be it a single piano or full orchestral work and the L-550A-II has no difficulty in being totally believable irrespective of the music being played.