By Lam Seng Fatt
From the outset I have to say that the Luxman L-550AXII pure Class A integrated amplifier sounds much more powerful than its rated 20 watts per channel.
It could drive my resident ATC SCM50 floorstanders, which have sensitivity of 85dB, to reasonable loudness levels. However, after a while I decided to opt for more sensitive speakers and managed to get a pair of Xavian Perla Esclusiva bookshelf speakers from AFC Top Hi-Fi which are 88dB in sensitivity with the manufacturer’s recommendation to drive them with amplifiers of minimum 30 watts per channel. It turned out to be a quite good match with the Luxman L-550AXII integrated amplifier being able to drive them to rather loud levels.
Being pure Class A, the Luxman can get quite hot after an hour or so of playing. But being pure Class A also means the sound quality is warm, dense, coherent and fluid. I recall listening to The Corrs Unplugged CD and remarking that the vocalists sounded rather natural and fluid. I then played a James Taylor Greatest Hits CD and he too sounded very fluid.
This dense and fluid sound was apparent even through the Audio Technica ATH M50x headphones plugged into the headphone jack of the Luxman. So late at night, I usually switched to listening with the headphones with the same amount of satisfaction.
Since I discovered in my earlier review of the Luxman L-505uXII integrated amp ( see
http://av2day.com/2020/03/luxman-l-505uxii-one-of-the-best-integrated-amps-in-the-market/) that Luxman integrated amps sound best when used as an integrated amp, I did not bother to check out the pre-out and main-in features of the Luxman L-550AXII integrated amp.
However, when I tested the built-in phono section of the L-550AXII with my tweaked Rega Planar 3, RB250 tonearm and Benz Glider MC cartridge, I found that it sounded better than the phono section in the L-505uXII. So if spinning LPs is not your main source of music, then buying an outboard phono preamp may not be necessary if you own the L-550AXII.
The L-550AXII integrated amp uses proprietary technologies such as the new LECUA1000 computerized attenuator and the ODNF version 4.0 innovative amplification feedback circuit which features a fast primary slew rate and an ultra-wide bandwith achieved through the feedback of distortion components only from the output signals.
The integrated amp also has a high-inertia power supply circuit that combines a large capacity EI core type power transformer (to which a vibration control feature has been newly added) and a large capacitor block (10,000uF x4). In its output stage is a discrete buffer circuit to protect the purity of the audio signals whilst simultaneously enhancing the drive force for the power amplifier.
While the warm, dense and fluid sound quality can be very appealing, there are some limitations which are purely characteristics of the design such as the bass. Though there is sufficient bass weight and the quality of it is tuneful and not one-note or too fat, the Class AB integrated amps like the Luxman L-505uXII offer tighter and deeper and slightly leaner bass. Also the Class AB amps sound less dense and thus offer more transparency and openness, especially in the treble region.
So should you go for the Class A or the Class AB Luxman integrated amps? They have different sonic flavours. If you buy this 20-watter L-550AXII or the ‘big brother’ L-590AXII, a 30-watter, you will need to use speakers of at least 88dB in sensitivity even though the Class A integrated amps sound more powerful than the numbers suggest. If your speakers are not that sensitive and are harder to drive, and if you prefer a stronger bass and more transparency, then the Class AB models would be a better choice.
The Luxman L-550AXII Class A integrated amp retails at RM25,500 net and is available at CMY Audio & Visual.