What’s crackin’ PAR fam? In this review, I’m checking out the Phatlab Chimera tube and JFET dual-mode portable headphone amplifier. The Chimera has a bunch of interesting features, in particular, a seamlessly switchable Triode and JFET gain stage. Other features include a 4.4mm balanced output, high output power plus low and high gain modes, making it compatible with sensitive in-ear monitors as well as demanding full-sized headphones.

Over the past few years, portable HiFi has continued to grow in popularity and complexity. Nowadays, people want a more diversified approach to their music listening with the option to take the music with them when they’re on the move. In addition, they want to be able to switch between various headphones and earphones while using the same source. Enter the Phatlab Chimera.

Phatlab website: http://www.phatlabaudio.com/

This sample was provided for the purpose of an honest review. All observations and opinions here are my own based on my experience with the product.

Phatlab Chimera Review

Build Quality and Design

In terms of the physical build, the Phatlab Chimera is CNC machined in a brushed aluminium chassis. The net weight is 370 g for the regular version and 378 g for the Chimera D which has a built-in ESS9028 DAC module. In this review, I’m looking at the regular version.

Chimera feels good to pick up and the rounded, ridged sides of the amp allow you to get a solid grip on it; after all, you don’t want to drop it on your way from the living room to the back patio!

On top of the unit is a clear rear-printed window that emits the orange glow of the JAN6418 tubes inside. On the underside are four rubber feet that keep the Chimera firmly in place on your desk, table, counter or whatever you decide to place it on.

The front panel contains (from left to right):

• 3.5mm single-ended output
• 4.4mm balanced output
• Gain switch: Hi: 14dB (3.5mm), 20dB (4.4mm) / Lo: 6dB (3.5mm), 12dB (4.4mm)
• 3.5mm line-in
• Power and low battery LED indicators
• Volume pot

On the rear panel are the JFET/Tube gain stage selector switch, a battery charging LED indicator and the Micro-USB charging port.

Internals and Features

Chimera is unique in that this portable amp can switch between tube and solid-state gain stages immediately, on the fly with the flick of a switch. Platlab introduced an innovative circuit topology to embed both devices exactly in the same location in the signal path. Being able to switch modes like this really makes it easy to hear the difference between tube and JFET stages.

Compared to the Phatlab Sassy II, Chimera’s new architecture and physical implementation deliver a lower noise floor. In addition, Chimera’s amp consumes 30% less power. However, it has the power to drive even the most demanding headphones while preserving the audio quality.

So how much power are we talking about here? How about 500 mA per channel at 30 ohms (from the balanced output)? You’ve got it. Yes, the Chimera can power pretty much anything you throw at it.

Versatile

But the beauty of Chimera is that it can also be used with even in-ear monitors (IEMs). Its output impedance is less than 0.1 ohm which is perfect for super sensitive multi-BA IEMs.

There is some channel imbalance until the volume pot is around 5 o’clock (off position is 3 o’clock). This means that if you want to listen to a sensitive IEM at low volume, you’ll have to lower the source volume in order to push the Chimera’s pot past 5 o’clock. This is only possible with a variable level line out from the source.

Finally, the Chimera has a frequency response of 10 Hz – 100 kHz, so you’re getting the entire dynamic range and the full bandwidth of your music without any compromise.

Battery Life

The Chimera’s battery life is rated at over 10 hours and I found that I was consistently getting more than that. This will depend, of course, on the efficiency of the headphones or IEMs that you’re using. Charging time for the battery is approximately 3 hours. I would have preferred to see a Type-C USB port instead of the Micro-USB but that will have to go on my wishlist for future models.

Sound

All that other stuff is fine and dandy but let’s get to the meat of this review: the sound. For testing, I used the following sources:

• PC -> Singxer SDA-2 -> RCA to 3.5mm cable -> Chimera
• Soundaware M2Pro balanced Pure Line Out -> 3.5mm interconnect cable -> Chimera
• iBasso DX120 -> Line Out -> 3.5mm interconnect cable -> Chimera
• Shanling M0 Line Out -> 3.5mm interconnect cable -> Chimera
• Samsung Galaxy smartphone -> 3.5mm interconnect cable -> Chimera

I have to say, listening to full-size planar headphones using the Chimera with my phone as the source feels quite liberating. For a brief moment, I even questioned whether I need a DAP anymore: at least when I’m at home or in the office. However, I like having audible notifications enabled on my phone so that idea got binned very quickly (the Chimera Digital version would remedy this). I must admit though, this combo sounded great.

JFET Mode

In JFET mode, Chimera sounds more direct, very accurate and transparent. It has a well-balanced sound with fantastic dynamic expression and articulation. It’s the kind of sound you would expect from a full-blown desktop amplifier, making the fact that you can pick it up in one hand and move to another location all the sweeter.

The sound will change slightly depending on which DAC/DAP source you’re using. For example, the Soundaware M2Pro has a fuller, sweeter and more resolving sound, while the Shanling M5s is closer to neutral and more asserted.

Chimera has a clean, pure black background with no audible noise floor or hiss. It sounds precise and insightful without being analytical. Listening to Airbag’s “Homesick I-III“, Chimera sounds expressive and full of detail. It’s tight yet full-bodied, delightfully detailed and fluid.

There’s one other added benefit of having a JFET mode: when in motion, JFET can provide a steady performance on all occasions. Tube mode is designed primarily for stationary use because the slightest bump can cause a high-pitched ringing noise in the tubes. However, JFET is not affected by bumps for movement and can be handled like any portable amp.

Tube Mode

Switching to tube mode, Chimera suddenly becomes slightly ethereal in its presentation. The sound becomes softer, more passionate and emotive. Bass notes lose some of their immediacy and sound smoother but also fuller. Instrument and vocal notes become larger in size but so does the soundstage.

As with JFET mode, the noise floor is inaudible, providing a silent, black background. The sound is bathed in the organic glow of the tubes but loses none of its clarity or detail. Electric guitars still bite and hi-hats and cymbals ring purely and clear as a bell.

Then there are the vocals, which Chimera romanticizes and makes more intimate. It’s almost as if you’ve moved one row closer to the stage. With a song like Lunatic Soul’s “Under A Fragmented Sky” Chimera’s tube mode makes it sound even more mellow and engaging. I found myself sitting here with my eyes closed and singing along to the music and almost felt annoyed when the song came to an end.

Soundstage

The Phatlab Chimera’s soundstage feels expansive in both JFET and Tube modes. Using the JFET setting, the stage is a little smaller but the imaging and positioning are more precise. In Tube mode, the stage dimensions expand outwards, especially in width, but note size is increased too, so instruments and vocals fill up more of the available space.

Headphones Pairing

Thieaudio Phantom (planar magnetic driver, impedance 47 ohm, sensitivity 93±3 dB). Phantom is not particularly demanding when it comes to power but it’s not the most efficient headphone either. I used the 4.4mm balanced output on low gain and even then didn’t go past 6 o’clock on the volume pot (power off is at 3 o’clock). Since the Phantom already has a warm tonality with a thick midrange and average imaging, I found they worked best with JFET mode. The sound is mid-forward, rich, vibrant and full-bodied.

BLON B20 (planar magnetic driver, impedance 32 ohm, sensitivity 96dB). Slightly more efficient than the Phantom, the B20 has a leaner, more pronounced presentation with more clarity and brightness. Using the 4.4mm balanced output on low gain, I again had the volume pot at 5-6 o’clock. I like this headphone with tube mode as it fills out the sound, giving it more body and depth.

Beyerdynamic DT 990 Pro (dynamic driver, impedance 250 ohm, sensitivity 96 dB/mW). The DT 990 Pro is a bit more demanding than my planar headphones when it comes to driving power but not by a great deal. Since it has a fixed, unbalanced cable, I used the 3.5mm SE output on low gain and still only hovered the pot around 7-8 o’clock. These headphones have a V-shaped signature with elevated bass and lifted treble. I liked the tube stage with these as it softened up the bass a tad and smoothed out the treble a little bit. In addition, the midrange is slightly more forward with the tubes.

Hifiman Sundara (planar magnetic driver, impedance 27 ohm, sensitivity 94 dB). While Sundara is reasonably easy to drive, it does like a bit of power to bring out its full potential. I stuck with the stock 3.5mm cable and set the Chimera on low gain. Hovering the volume pot around 6-7 o’clock was plenty loud enough for my taste. I love the even tonal balance of the Sundara and I found myself switching between JFET and Tube modes with these depending on the music I was listening to, although I could happily live with either.

IEMs Pairing

DUNU DK-3001 Pro (hybrid 1 Berylium dynamic and 4 balanced armature drivers, impedance 20 ohm, sensitivity 112 dB). These obviously don’t need any additional amplification but hey: we’re allowed to be extreme sometimes right? Besides, man, do they sound good with Chimera’s tubey goodness! To be fair, they sound amazing in both modes but I used Tube for the majority of my testing with these. Using the 4.4mm balanced output, I found that I needed to use a source with variable level output in order to be able to keep the levels down so I could push the pot past 5 o’clock to avoid any channel imbalance. However, with the 3.5mm output, it was just right (it’s 6 dB lower than the balanced output) and worked fine with a pure Line Out.

Tin Hifi P1 (planar magnetic driver, impedance 20 ohm, sensitivity 95 dB). Notorious for being power-hungry the P1 is an IEM that truly benefits from the power on tap granted by Chimera. I stuck with the stock cable and the 3.5mm output on low gain and even with these little beasties, I was still only hovering between 5-7 o’clock on the volume pot. It’s a well-known fact that the P1 needs power for optimal performance but I was still surprised how good these sound with Chimera’s Tube stage. It has made me fall in love with this IEM all over again.

Comparisons

Phatlab Sassy II

Let’s start with the physical dimensions first. Sassy II is the same width as Chimera but it’s shorter in length and height. It’s just a little lighter as well. Size aside, the big difference with the Sassy II is the lack of any JFET gain stage, making it Tube only. The main takeaway from this is that Sassy II isn’t really suitable for motion or movement (the slightest bump causes the tubes to start ringing).

The same thing happens with Phatlab Chimera when it’s in tube mode. However, switching to JFET eliminates any ringing, thus it can be used just like a regular portable amplifier. Additionally, Chimera gets the benefit of two distinctly different sound signatures.

In terms of sound, Sassy II is extremely similar to Chimera’s tube mode and to be honest, I’m not certain I could tell them apart in a blind test. Although Sassy II has a higher noise floor, I’ve never heard any background noise from it, even with sensitive IEMs.

When it comes to output power, Sassy II actually boasts the same 1000 mW @ 30 ohms. That’s impressive, considering Chimera needs two more amps (to drive the negative polarity) in balanced mode to reach the same level.

Conclusion

The Phatlab Chimera is perfect for anyone looking for a portable and powerful headphone amp. With the option to switch between tube and JFET modes on the fly, it’s versatile too. It’s compatible with all types of headphones and IEMs, whether they’re warm and thick or bright and analytical; you can choose whichever mode fits best.

You’re not confined to any particular type of DAC either: Chimera can be paired with a beastly desktop unit or any portable DAP. Heck, it can even turn your smartphone into a truly capable audiophile-grade source. It’s not the most wallet-friendly, I concur, but I highly recommend it to anyone who wants a no-compromise amplifier with the freedom to take it anywhere.

Specifications

Frequency Response	10 Hz – 100 kHz
Output power (30 ohm)	300 mW + 300 mW (3.5φ) 1000 mW + 1000 mW (4.4φ)
Headphone impedance	30 ohm – 600 ohm
Gain Setting	Hi: 14dB (3.5φ), 20dB (4.4φ) Lo: 6dB (3.5φ), 12dB (4.4φ)
Max. S/N Ratio	>110 dB
Power supply	5V/1A via micro USB port
Operation time (on battery)	> 10 hours (amp alone) ~ 5 hours (amp + DAC)
Charging time (>1A supply)	Approx. 3 hours
Dimensions (WxHxL)	94 x 30.5 x 149 mm
Net weight	370 / 378 (D) g