Luxman SQ-N150, the Tube Amplifier that’s Heating up Music

Luxman was established in Japan nearly 100 years ago. Active in the audio field ever since, the company has become known for, among other things, its vacuum tube amplifiers, which have never ceased to be present in their catalogue. Some may also remember their vacuum tube CD-players in the 80′s and 90′s.

Their catalogue is currently quite comprehensive, with vacuum tube amplifiers alongside transistor, power, and integrated amplifiers as well. They also offer preamplifiers, CD players, D/A converters, and headphone amps. Luxman offers a vast selection of resolutely high-end products that are less accessible to the general public than they were twenty or thirty years ago. Nevertheless, you can get a feel for the brand through this “little” SQ-N150 that we’ve tested here.

Overview of the SQ-N150

The vintage effect is in full force with the SQ-N150. One first takes notice of the hallmarks of Luxman products with their emblematic silver-gray applied to the entirety of the unit’s body and each of its buttons. Next, a clear highlight is the protective casing of the vacuum tubes; one can discern the six tubes hidden beneath, which shine brilliantly once the amplifier is started up. Behind them are the output jacks as well as the power cable, found beneath distinct, sealed boxes.

The SQ-N150 measures a mere 29.7 cm from the side, approximately the size of an A4 sheet of paper, but it makes up for it with a height of nearly 19 cm. It’s a device to be shown off, but that has to breathe for the heat from the tubes to dissipate. It will sit regally atop a piece of furniture, perhaps best-situated beside a turntable. The pairing makes sense and will never lose its charm. We also buy Hi-Fi devices because we like the design.

To perfect its retro appearance, the SQ-N150 also features small level meters, backlit in the yellow-orange color characteristic of Luxman products. A small button situated right beside them allows for these lights to be turned off if need be. The volume potentiometer is placed on the right-hand side, accompanied by a headphone jack and the infrared remote control sensor.

Luxman has placed the main controls on the top panel of the amplifier. A high-quality lever serves as a selector between the four available input sources. Note that the phono input is both MM and MC compatible, which is reflected in the selection choices for this lever. Next, three line inputs round things off. All of these inputs are asymmetrical on RCA jacks.

The internal design follows the brand’s usual principles for vacuum tube amplification. The input circuits make use of two JJ Electronic ECC83 tubes placed in front. The four large tubes at the back are for power. Luxman has chosen JJ Electronic EL84 tubes to put in place here. These tubes, featuring the Luxman logo, have been used and recognized for many years in the Hi-Fi world. There’s nothing extravagant here, simply time-tested solutions.

Using the SQ-N150

Found on the top panel of the SQ-N150 are three potentiometers for just as many settings: bass, treble, and balance. All of this can be deactivated via a “line straight” button that makes the signal take the shortest pathway possible. The SQ-N150 goes back to basics. No frills to be found, and there’s no risk of getting lost in the functionalities.

You may have also noticed that it’s missing a DAC, and consequently, digital inputs. In order to enjoy Qobuz, you must link it up with a DAC streamer with analog RCA outputs, or separate the two: a streamer with digital outputs and an independent DAC. As far as vinyl goes, you need a turntable with an integrated RIAA preamplifier, or to add this onto the signal pathway.

The SQ-N150 is not 100% vintage either, and Luxman has provided an infrared remote control for this connected vacuum tube amplifier. The remote also doesn’t have an on-and-off function, as the button on the device is mechanical, which is mandatory on account of the heating phase of the tubes, during which the small LED of the volume potentiometer flashes. The sound will be interrupted during this start-up phase.

The input selector, originating from the brand’s high-end C-900u preamplifier, to be clear, is mechanical. Ultimately, the remote simply controls the volume. The “mute” button will always be useful, whereas the other available buttons are dedicated to controlling a Luxman CD player, such as the D-07X that we had tested only a year ago, or the D-N150 that takes on the same style of this amplifier, minus the tubes. These players have the advantage of making use of a DAC for other digital input sources. Lastly, it goes without saying that the SQ-N150 has neither Bluetooth nor a mobile control app.

The advertised power output caps at 2x10 watts, which seems quite weak on paper, given the current era where the class D and its extremely high power are the norm. The tubes utilized in the SQ-N150 and its compact format limit possibilities. Nevertheless, these 2x10 watts are sufficient for listening at “normal” volume in rooms between about 10 and 25m². Obviously, the more sensitive the speakers, the better the result will be. High-output speakers are preferable, like ones from Klipsch or Tannoy, but the SQ-N150 will work with classic models as well.

Listening Experience

We connected up our usual Dynaudio speakers. On paper, they don’t quite meet the requirements for the SQ-N150 on account of their weak output and their impedance of as low as 4 ohms, Luxman recommending a minimum of 6 ohms. If one sticks to a moderate usage, there’s nothing to fear. We linked it up to a streamer with an independent DAC in order to use Qobuz through Roon. We finished our listening session with different headphones.

The first thing to do was to adjust the output level of our DAC, which was too high by default and was causing distortion. Once that was equalized, the music was ready for listening. We kicked things off with M’s live album En Rêvalité. The acoustics are vast, without being too precise, which gives off a certain presence and warmth. The vocals are well-isolated, whereas the audience fills out the background. The SQ-N150 perfectly reconstructs the live music effect, minus the high volume.

This vacuum tube built-in is more at ease with recordings in more intimate settings, such as the Qobuz Sessions at SXSW with Yazmin Lacey on the mic. This type of device’s positive qualities are all found on this type of acoustic-adjacent recording, featuring vocals paired with a Rhodes-like keyboard. The SQ-N150 loves simple, gentle phrases and will bring out every nuance and depth. You can then fully enjoy the music as if you were there.

The Jalapeno Funk compilation lets us test it out at a different register. Here’s something that could stir up the SQ-N150, but it manages brilliantly. Despite its limited power, it offers stunning support for the bass, which makes it perfectly suited for funk, electro, and other similar musical genres. It doesn’t infinitely descend into the depths of bass, or up to the extremes of treble, but it reproduces percussion with force and accuracy. It’s simply what we expect of high-end music reproduction.

The reproduction of Dvorak’s Slavonic Dances by the Prague Symphony Orchestra presents the device with a bit more of a challenge. It manages to reproduce a large stage relatively well, without going as far as giving a sense of every single musician’s chair. Overall, it’s pleasant, but as soon as the dynamic levels take off, it struggles a bit with differentiating between instruments. Again, the device seems more at ease with a jazz trio than with metal or house music.

We found the same results with headphones. Just as with speakers, it’s useful to specify that pairing with the right headphones will be critical to obtaining results that meet your expectations. Closed Focal headphones were much more appropriate than open planar ones from Sivga. The SQ-N150 is not a universal integrated amp; one must be careful with the components of the system surrounding it.