TEST: SPL Phonitor XE

 A review of an SPL product made in Germany is always a particular pleasure for me, not only because of the guaranteed high manufacturing quality but also due to the 50% disapproving comments about the consistently high prices of the Niederkrüchten-based company. The two camps quickly become irreconcilably opposed, essentially repeating their arguments in a mantra-like fashion, with "Product XY is much cheaper and just as good" on one side and "But it's the best there is" on the other. Whether this product will lead to another such discussion remains to be seen in the upcoming test. After all, the SPL Phonitor XE comes with a retail price of €2,099 and, depending on the version, ranks among the top 4 or top 9 most expensive headphone amplifiers in the Thomann music store's portfolio.

The Concept of the SPL Phonitor XE

It's likely known to every reader that SPL has held a firm place in the top league of headphone amplifiers for decades, especially since the Phonitor series secured a permanent spot in many pro studios with the introduction of the legendary matrix circuit. With the SPL Phonitor XE model, SPL is now bringing a new flagship to the market. Unlike its counterpart, the Phonitor X, which can also function as a preamp for signal distribution with its XLR outputs, the XE functions as a pure headphone amplifier. Needless to say, at this price point, the focus is on meeting the highest standards.

The buyer has a choice between two models, with and without a D/A converter, with the integrated DAC768 converter adding €700 to the price. Which model to prefer primarily depends on the personal setup of the studio. If you haven't installed a converter yet, it's worth considering the second variant. Like all other top-tier products from SPL, the SPL Phonitor XE also runs on the patented 120 V technology, which provides a significantly more relaxed headroom during operation.

The fact that SPL has expanded its competencies beyond the pro sector, particularly in the Hi-Fi sector in recent years, is evident in the product's visual appearance, along with the typical "plate feet" that have been used in the Hi-Fi sector for ages. The SPL Phonitor XE thus visually demonstrates its dual orientation, targeting two groups: the pro user in the recording studio and the ambitious Hi-Fi fan. The general visual impression is correspondingly "massive," impressively underlined by a weight of nearly 5 kilograms. For a wider visual selection, the product can be purchased in black, silver, and red to match the respective ambiance.

The first special feature of the SPL Phonitor XE is found on both the front and back of the amplifier in the form of a digital XLR-4 headphone output, which is present along with a standard TRS output. A mini-switch on the front of the housing allows you to choose whether to connect your headphones on the front or the mirrored back. A real blessing when I think about how often the headphone cable stretching across the desk has gotten on my nerves.

The Rear Panel

In terms of connections, SPL exhausts the entire bandwidth, except for the TRS connectors that are almost never used in this segment. For the analog area, there are lockable, balanced XLR sockets in addition to gold-plated RCA connectors (RCA and then gold-plated, actually a contradiction in itself ;-). In the digital realm, the product offers 4 different ways to process the signal with AES, Coaxial, optical, and USB.

The possible conversion rates of the built-in D/A converters from AKM (AK4490) are as follows:

AES/EBU (XLR), PCM sampling rates: 44.1 / 48 / 88.2 / 96 / 176.4 / 192 kHz
Coaxial SPDIF (RCA), PCM sampling rates: 44.1 / 48 / 88.2 / 96 / 176.4 / 192 kHz
Optical SPDIF (Toslink F06), PCM sampling rates: 44.1 / 48 / 88.2 / 96 / with fiber optic < 1m: 176.4 / 192 kHz
USB (B), PCM sampling rates: 44.1 / 48 / 88.2 / 96 / 176.4 / 192 / 352.8 / 384 / 705.6 / 768 kHz
USB (B), DSD over PCM (DoP), sampling rates: 2.8 (DSD64), 5.6 (DSD128), 11.2 (DSD256) MHz

There's also a push button for IR programming, allowing any standard remote control to be used for controlling the headphone amplifier. Additionally, there's the IEC socket, the power switch, and the corresponding voltage selection. To activate the product from the front as well, SPL has installed an additional standby mini-switch on the front panel.

The Front Panel

Always a welcome sight, but besides their retro look, also electronically a highlight for me personally due to their comparatively sluggish response: 2 VU meters, separate for the right and left channels. Depending on the incoming level, the displays can be adjusted in sensitivity by 6 or 12 dB via a mini-switch below the left VU meter. Since the SPL Phonitor XE is designed for the classic solo producer in the studio, the device only has one headphone output each, which can adequately cover headphones in the lower double-digit as well as the higher triple-digit ohm range.

Here's a brief list of the key data for headphone operation:

XLR 4 (digital)
Source impedance: 0.36 Ω
Damping factor (40 Ω): 180
Frequency response (-3 dB): 10 Hz – 300 kHz
Crosstalk (1 kHz): -90 dB
THD + N (10 Hz – 22 kHz, 0 dBu): 0.00082 %
Noise (A-weighted): -98 dBu
Output power (1 kHz, 1% THD, 600 Ω): 2 x 8 W
Output power (1 kHz, 1% THD, 250 Ω): 2 x 3.5 W
Output power (1 kHz, 1% THD, 32 Ω): 2 x 0.7 W
Dynamic range: 130.5 dB

TRS
Source impedance: 0.18 Ω
Damping factor (40 Ω): 180
Frequency response (-3 dB): 10 Hz – 300 kHz
Crosstalk (1 kHz): -90 dB
THD + N (10 Hz – 22 kHz, 0 dBu): 0.00082 %
Noise (A-weighted): -103 dBu
Output power (1 kHz, 1% THD, 600 Ω): 2 x 2.7 W
Output power (1 kHz, 1% THD, 250 Ω): 2 x 5 W
Output power (1 kHz, 1% THD, 32 Ω): 2 x 1 W
Dynamic range: 135.5 dB

The eye-catcher on the front is the Alps-RK27 level control, which turns with the famous "spoon in a honey jar" feel. The left front side is dominated by the input selection and a triple panorama selection (Mono, Stereo, and Laterality with Stereo Sum Panorama rotary control) from the SPL matrix. In this device, the matrix has been limited to the Crossfeed (crosstalk degree of the simulated monitors) and Angle (angle of the stereo triangle) controls. Additionally, the matrix can be switched on and off with a mini-switch. Lastly, the product has two DIP switches on the bottom of the housing, which can be used to adjust the input level for the RCA input (-10dBV/0 dBu) and boost the headphone output with a level increase of 22 dB.

The SPL Phonitor XE in Practice

Let's start with the haptics of the product. As expected, all controls and switches of the SPL Phonitor XE meet the highest standards. The controls are grippy, engage cleanly, and convey a very high-quality feel during switching. The same applies to the switches, which, above all, do not exhibit the notorious "wobble" of less expensive counterparts.

Sonically, the result can be summed up in one word: outstanding! It's hard to put into words how relaxed, detailed, and yet voluminous the SPL Phonitor XE sounds in its entirety. On my Beyerdynamic T1 reference headphones, the amplifier impressed in all aspects and at all volumes. It particularly excelled in terms of dynamics and allowed for relaxed work over several hours without any problems.

A quick word about two special features of the SPL Phonitor XE: the adjustable stereo balance and the matrix. People with hearing impairments will particularly benefit from the Laterality control, as they can find an appropriate stereo center using this control at the first signs of asymmetric deafness. An unusual but very helpful bonus for the affected target group.

The matrix, on the other hand, remains the secret star of the Phonitor series, as it manages to bring together the always unnaturally sounding phantom center of the extreme stereo arrangement of the individual speakers into a naturally sounding result. As is known, there is no situation in nature where a corresponding spatial effect would not be shown due to time delay, which makes the listening pleasure of a signal appear significantly more natural in terms of depth layering. Definitely worth a listen!

Additional Insights

The SPL Phonitor XE's 120V technology deserves a closer look. This patented approach significantly increases the operating voltage compared to standard designs, resulting in several benefits. The higher voltage allows for a larger dynamic range and lower noise floor, which translates to a cleaner, more detailed sound. This is particularly noticeable when listening to complex musical passages or during critical mixing sessions where every nuance matters.

The matrix circuit, a hallmark of SPL's Phonitor series, is more than just a gimmick. It addresses a fundamental issue in headphone listening: the unnatural stereo image that results from having two isolated channels delivered directly to each ear. By simulating the crosstalk and time delays that occur in speaker listening, the matrix creates a more natural, speaker-like experience. This is especially valuable for mixing engineers who need to make critical decisions about stereo placement and depth.

The Laterality control is an often-overlooked feature that can be a game-changer for some users. Beyond its utility for those with hearing impairments, it can be useful in various scenarios. For instance, it can compensate for slight channel imbalances in headphones or recordings, or it can be used creatively to adjust the stereo image without affecting the overall volume.

Build quality is another area where the SPL Phonitor XE shines. The use of high-quality components throughout, from the Alps potentiometer to the gold-plated connectors, ensures not only excellent sound quality but also long-term reliability. The robust construction and attention to detail in the design speak to SPL's commitment to creating professional-grade equipment that can withstand the rigors of daily studio use.

The inclusion of both XLR and TRS headphone outputs provides flexibility for users with different headphone terminations. The ability to switch between front and rear outputs is a thoughtful touch that can significantly improve cable management in cramped studio environments.

While the SPL Phonitor XE is primarily designed for professional use, its features and sound quality make it equally appealing to discerning audiophiles. The combination of high power output, low noise floor, and the unique matrix circuit can breathe new life into high-end headphones, revealing details and nuances that might be missed with lesser amplifiers.

The DAC option is worth considering for those looking to simplify their signal chain or upgrade their digital-to-analog conversion. The AKM AK4490 chip used in the DAC768 version is well-regarded in audiophile circles for its natural, musical sound. Its ability to handle high-resolution PCM and DSD files makes it future-proof for those with extensive digital music libraries.

One potential drawback of the SPL Phonitor XE is its size and weight. While this contributes to its solid build and impressive performance, it may not be ideal for those with limited desk space or who need a more portable solution. However, for those who can accommodate it, the substantial build inspires confidence and helps to isolate the sensitive audio circuitry from external vibrations.

The price point of the SPL Phonitor XE places it firmly in the high-end category, which may put it out of reach for some users. However, when considering its build quality, performance, and unique features, it represents good value for professionals and serious enthusiasts who demand the best possible headphone listening experience.

In the context of SPL's product line, the Phonitor XE represents a sweet spot between the more affordable Phonitor models and the top-of-the-line Phonitor x. It offers most of the features and performance of its more expensive sibling but in a more compact form factor and at a lower price point.

Conclusion

The SPL Phonitor XE once again sets the bar very high for the competition. The amplifier sounds outstanding in all respects, is excellently crafted, and offers two bonus features with the Laterality control and the Matrix circuit, which crown an already very high-quality product.

For professionals working primarily with headphones, the SPL Phonitor XE could be considered an essential tool rather than a luxury. Its ability to provide a speaker-like experience through headphones can significantly improve the accuracy of mixes and reduce ear fatigue during long sessions.

While the price may be a barrier for some, those who invest in the SPL Phonitor XE are likely to find it a long-term solution to their headphone amplification needs. Its versatility, build quality, and unique features make it a product that can grow with the user's needs and continue to provide value for years to come.

In the realm of high-end headphone amplifiers, the SPL Phonitor XE stands out not just for its technical specifications, but for the thoughtful design choices that address real-world needs of audio professionals and enthusiasts alike. It's a product that demonstrates SPL's deep understanding of both the science of audio and the practical needs of its users.

Absolute top class!