_{Prices listed in US$.}

One of the comments I expected after my first installment on budget components was “How much does the Chinese government pay you for these reviews?” Although that email never came, I suspect it was in some readers’ minds. So, for the record, I do not receive any payments from manufacturers (or foreign countries) for my reviews here. Instead, everything I’ve reviewed so far, except for the Fosi ZA3, I have purchased. Occasionally, I receive a discount of 10% from APOS Audio on components I’ve previously reviewed if I wish to purchase them, but that is roughly the same discount pricing APOS offers to the general public on demo units.

Like Consumer Reports, I prefer to buy the components I review here. They are priced so that I can afford to buy them outright, so I do. When I’ll review something I don’t own, I’ll let you know.

Aiyima SMSL E600 fully balanced headphone amplifier

$106 – $148 (depending on op amps), plus $57.20 shipping

I bought this headphone amplifier years ago but gave it away as part of a system for a relative. I’ve included it in my survey because, unlike several other headphone amplifiers I’ve purchased through Ali Express and wanted to recommend, this one is still available. The linked listing is for 220 AC, but switching to 110 AC is available for a small upcharge if you contact the seller.

The E600 includes both balanced XLR and single-ended RCA inputs, and both balanced and single ended headphone connections. Specifications are decent, with a 102 S/N and 1500 mW capability. The site I’ve linked to has three different versions with different op amp options. Frankly, I don’t remember which op amp my unit contained. (The Ali store I bought it from has closed so I can’t go back to the original posting). I would recommend getting the less expensive unit and replacing the stock op amp with a Sparkos or Burson one if your goal is to optimize this design.

Since the E600’s sound is dictated primarily by its op amp choice, depending on which op amp you use, the sound will be different. My stock unit sounded decent, but with a slightly closed-in top end and constricted soundstage width that a better op amp would have improved. And while the E600 certainly had adequate gain for my Sennheiser HD600, I would have liked a little more power for my Dan Clark Stealth that a better op amp could have delivered. But even with the stock op amp, the E600 has a well laid out circuit topology with an above average transformer and volume control which makes it ideal for upgrades.

Topping EH-5 Electrostatic headphone amplifier

$399

When I saw the first announcement of this amp, I immediately pre-ordered one. My ardour was rewarded with an amplifier that worked for exactly one day before failing. I purchased it from APOS Audio, who handled the warranty replacement without any hassles. The second unit has been reliable for the past five months…

I’ve read that it’s virtually impossible to make a good electrostatic headphone amplifier without employing certain expensive technologies, and the Topping design was bound to be inadequate due its circuit topology. One headphone manufacturer even told me flat out, “It won’t work with our headphones.” So far, that has not been the case for me.

I’ve used the EH-5 with a pair of Dan Clark Audio Corina and Stax SR-009S headphones using the lower gain setting (it has low and high gain settings). While there may be some electrostatics the EH-5 can’t successfully drive, the Corina and Stax are not part of that group. The sound through them has always been clean and clear, and I’ve never felt the amplifier getting in the way of my listening.

I’ve never been enamoured by the sound of entry-level Stax solid state headphone amplifiers. They all sounded a bit dark and murky to me compared to Stax’s tube-based amps, like my SRM-007t. In terms of transparency, the EH-5 sounds better in terms of transparency compared to Stax entry-level amps I’ve heard, but it does not have the depth recreation, solidity and “puff of air” quality to the bass that I hear through the Stax SRM-007t. Still, when you consider its cost, the EH-5 makes it possible to get into an electrostatic headphone system at a much lower price point. Coupled with the Stax L-300, the EH-5 moves the cost of entry for an electrostatic system to under $800.

 xDuuo X-20 tube headphone amplifier

$499 w/standard tubes, $648 w/Apos Ray 12AU7 tubes

XDuuo makes a whole bunch of small audio components linked by their sturdy metal cases and red volume knobs. The X-20 combines a tube rectifier with a fully balanced circuit. I liked the specifications, design, and feature set so much that I went early-adopter and purchased the basic model pre-release. I got what I deserved when my first sample failed after a week. I went through the return/replacement process with Apos Audio, and my second sample has been working properly for the last couple of months.

After a week with the replacement unit, I replaced its stock set of 12au7 tubes with Apos Ray 12au7 ones. I did not hear any noticeable sonic differences, but the Apos Ray tubes have somewhat better transconductance numbers, so they have the potential to drive difficult headphones to higher volume levels with less distortion. The X-20 had no trouble driving both the Dan Clark Audio Stealth and the Beyer Dynamic DT990 600-ohm version to satisfying volume levels, with room to spare. Even with these harder to drive headphones, the X-20’s volume control never exceeded 55 on its 0 to 99 range.

Among the X-20’s features is a VU meter that shows the input level. I found this especially useful when trying to determine if the X-20 is receiving a signal. It also looks nice. Other features include both single ended and balanced inputs and a single-ended output. The RCA single-ended output lets you employ the X-20 as a tube-based line-level preamplifier with two single-ended and one balanced input capable of 18 dB of gain and 113 dB S/N. This hybrid design’s S/N specification rivals many all-transistor preamplifiers.

While some potential buyers will gravitate towards the X-20 for “that tube sound”, my experience with the X-20 was that it is far more neutral and “straight wire with gain” than I expected. Low frequencies were well controlled with little in the way of tube bloom in the midrange. I suspect the hybrid design, with a class-A solid state buffer, gives this unit a more matter-of-fact response than an all-tube design, such as my Dennis Had inspired Dragon IHA-1.

While gross generalizations are usually a bad idea, my personal experience with the early production runs of both Topping and XDuuo leads me to the opinion that the first samples off the assembly line of promised high-performance Chinese audio products will very likely have higher failure rates than examples manufactured later in the production run.

The next installment will include cool-running power amplifiers with a matching DAC and an AKM-based DAC that can upsample to 705.6 kHz…

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