I recently took delivery of the TEAC HA-501. After giving it a good workout, I am happy to share my impressions about it.
TL;DR
This is one impressive amplifier. It has clean, refined power. It is very musical with a hint of warmness and smoothness, while retaining a high level of detail. It is very transparent and essentially disappears from the chain.
Highly recommended.
Picture of My System
In the picture, you can see the TEAC HA-501, Bifrost Uber, iPod Classic, Pure i20, Trafomatic Head One, and Shure SRH1540.
Amplifier Basics
The TEAC HA-501 is a solid state amplifier. Key features include variable output impedance to control the damping factor for all headphones you own. According to fellow Head-Fi member Operabuff, the calculations for damping control range from a low output of 0.4 ohms to a high of 5.1 ohms. The idea behind it is when damping is set on high, the output impedance is the lowest, giving a more controlled and analytical sound. When set on low, the impedance is the highest, and the sound is more mellow and euphoric.
The circuit design uses Muses 8920 op amps, which are considered as "audiophile" op amps. While some audiophile purists may detest op amps of any kind, I have no objection to them.
Test Equipment
DAC: Schiit Bifrost Uber via coaxial from Apple lossless fed from iPod Classic and Pure i20 dock.
Headphones: Shure SRH1540 (closed) and Sennheiser HD650 (open). These were chosen because they represent both open and closed headphones with both high and low impedance.
Comparative Amplifiers: Schiit Asgard 1, Schiit Asgard 2, Woo Audio WA3, and Trafomatic Head One.
Bass
Overall, the bass is rendered in an excellent manner. It goes deep and is highly controlled. The bass notes are detailed and textured and are never one-note. The amplifier renders the different bass notes with precision. I can detect no bloat or leanness from the bass. Whatever is on the album is what the amplifier delivers. Drums are rendered with razor-like accuracy and punch. There is nothing left wanting from the bass regions. The textures from bass guitars are crunchy, yet throaty with authority.
Mids
The mids are exquisite. Voices, particularly female voices, are quite seductive. They are charming and smooth, yet they are brought to the forefront. Voices never get lost in the shuffle and are easy to track. Guitars have the appropriate crunch and distortion. I can detect no grain at all in the mids, which may also be a product of my test headphones because they are known for their lack of grain, but the amplifier certainly didn't introduce any grain when compared to my other amplifiers I have in my stable.
Highs
The highs are smooth and sweet. There is definitely no grain, and if the album lacks stridency, the amplifier certainly doesn't introduce any. If there is stridency and sibilance on the album, the amplifier will pass that along, but not completely honestly. It does smooth them out a little bit, which I consider a good thing. Cymbals, bells, flutes, and whistles are all smooth and sound as close to natural as I've heard them in my living room with my gear. All in all, the highs are beautifully rendered.
Soundstage
The soundstage is rendered as the album was recorded. It's neither artificially compressed nor expanded.
Control
I like to throw my amplifiers the torture test, which I find from Brian Eno and David Byrne's album "Everything That Happens Will Happen Today." The album is pretty much a torture test because it's such a complex collection. Most of the songs are a nexus of guitar, techno, electronica, deep bass, percussion, and of course David Byrne's magnificent voice. Lesser amplifiers fall apart on these tracks and lose focus. The result isn't pretty. When played natively on my iPod through its headphone jack, the iPod completely loses it. The Schiit Asgard 1 has trouble, but the Asgard 2 maintains much more control. Depending on the tubes used, the Woo may or may not have troubles with the album. If using the legendary Tung-Sol 5998 power tube, things go smoothly. However, rolling in an RCA 6AS7G reduces the control and precision. The Trafomatic Head One and TEAC have no problems slicing through these tracks. The torture test is passed with flying colors.
Damping Factor Control
I'm sure this feature will interest some potential buyers. I did try it out on both my low and high impedance headphones. While the effect is real, it is pretty subtle at best. It was more noticeable on the low impedance Shure SRH1540s than it was on the high impedance Sennheiser HD650s. It did work as advertised, I'd say. When on high, the sound was more crisp, and when on low, it was more euphoric. I preferred it on medium with the Shures and on high for the Sennheisers.
Noise Floor
The noise floor is very low. The amp doesn't introduce any noise on top of the noise already in my chain. Based on previous tests, the nosiest component in my chain is the Bifrost Uber. I can hear the noise floor when I crank the volume to high on the amplifier with music muted. The TEAC doesn't add anything to this as far as my ears can tell. Overall, I'd say the amplifier is very quiet and transparent. The low noise of the TEAC knocks the socks off the Schiit Asgard 1 and Asgard 2. The Woo, since it's an OTL amp using the noisy 6AS7G power tube is naturally noisy to begin with, and also has a slight veil to the sound.
Musicality
We can talk about tech specs for hours, harp on the noise, etc. But, what does it do for the music? It is very musical amp. It's very detailed, yet smooth. There is a hint of warmth, which I find pleasing. It feels like it has power in reserve, which can pull out the minute details in the background, but yet have the cannons explode with gusto during the 1812 Overture. While the amp pulls out every detail thrown at it, it never sounds clinical or analytical. It is fluid. Compared to my Trafomatic Head One, which is an output-transformer-coupled tube amp, the TEAC doesn't have the mid-tone bloom, but it does retain similar smoothness. It's perhaps a touch less holographic, but the soundstage width is about the same. I don't find the TEAC any less musical than the Trafomatic; it's just a slightly different flavor. I find the Trafomatic to be quite linear not very "tubey" in sound, so I find it to be a fair comparison.
The Woo is a pretty "tubey" sounding amp, so it's not really a fair comparison to match it up with the TEAC.
At the end of the day, the TEAC induces no listening fatigue. In fact, it has an addictive qualities. For the last week, I've been guilty of the "just one more song before bed" conversation with myself that would last for several hours. It's definitely a solid state amplifier, and may lag behind what tube amplifier fanatics live for, but the TEAC certainly stands on its own in the musicality department.
Other Thoughts
The TEAC is a well-built piece of equipment. It exudes quality, and those who have it will have a high level of pride in ownership. Potential buyers will be happy to know there's absolutely no transients or power on/off thumps, pops, bangs, or hisses. While those don't typically damage headphones, it's assuring to not have to hear them.
Comparisons
Other amplifiers in my arsenal include the Schiit Asgard 1, Asgard 2, Woo Audio WA3, and Trafomatic Head One. The TEAC literally puts the Schiits and Woo to shame. It has much less noise and more detail retrieval. I'm a Schiit fanboy, and I think highly of both Asgards, but the noise, precision, and control of the TEAC make the Asgards seem like much lesser amplifiers, and they are in the price category. No disrespect to the Asgards, but the difference is that noticeable. Same with the Woo, as it is noisy, lacks top-notch control, and can feel claustrophobic at times. The Trafomatic is a world-class amplifier in terms of musicality, control, soundstage, and its holographic nature. The TEAC gives it a run for its money. The TEAC has about the same low noise, detail retrieval, and spaciousness. Where the Trafomatic bests it are in the tube mid-tone bloom and the holographic imaging, but it's not by much.
Conclusions
Overall, this is a wonderful solid state amplifier made my major company. Many of us like boutique companies and components, myself included. However, you don't need to find a rare amplifier or circuit design to get good sound. The TEAC is a very musical amplifier. Whatever you throw at it, it will render accurately and with authority. It pulls out the finest details, yet has power in reserve to totally rock out. It is quiet, transparent, and you don't even know it's there. That's the sign of a great amplifier. TEAC swung big on this, and I say they hit a home run. You need not look exclusively to boutique and cottage industries for that elusive amplifier. The TEAC is well worth an audition.
