ACS Custom T2 Classic Custom-Fit In-Ear Monitor (Playback 61)

Superior Fit for Superior Sound

• An ALO Audio Rx Mk3B fully balanced portable amplifier fed by the combination of an iPod (loaded with lossless and/or full CD-res WAV digital audio files) and a Cypher Labs AlgoRythm Solo portable DAC.
• A Ray Samuels Audio SR-71B Blackbird fully balanced portable amplifier fed directly from an iPod (loaded with lossless and/or WAV digital audio files).
• A NuForce Icon iDo DAC/headphone amp fed by an iPod (loaded with lossless and/or WAV digital audio files) where the NuForce DAC—not the iPod’s built-in DAC—handled the job of decoding digital audio files.

We listened to the T2 Classic in comparison to many custom-fit IEMs and top-tier earphones, but focused especially on comparisons with the Ultimate Ears In-Ear Reference Monitors (IERMs), which serve as Playback’s reference standard for overall neutrality of tonal balance.

And the findings, please: Let’s begin by acknowledging that one key aspect of the ACS sound is the almost otherworldly, ultra-quiet listening background these monitors provide. In our experience, the T2 Classic has only one peer in this regard; namely, the Sensaphonics 2MAX/2XS monitors, which—like the T2 Classic—use soft gel (cold cure) silicone earpieces. In terms of absolute quietude, though, the factor tips the scales ever so slightly in favor of the ACS monitors is their “Full Concha” earpiece design, which gives a secure seal no matter how vigorously users might move around while listening. It sounds a bit hokey to say, but after a few minutes the T2 Classics almost seem to become part of you.

The T2 Classic offers what appears, at least in broad strokes, to be generally neutral tonal balance, but with three small yet audible strategic deviations from strict textbook neutrality. First, bass—and specifically mid-bass—is warmed up just bit in what we presume is an effort to give the T2 an extra touch of mid-bass weight and warmth. Second, upper mids and lower highs are likewise given a dab of extra emphasis, not enough to make the T2 Classic sound overtly bright or edgy, but enough to impart a heightened sense of focus and clarity. The one observable downside to this approach, however, is that the T2 can make upper harmonics of notes as well as certain hard, sharp transient sounds seem disproportionately forward sounding or even a bit brittle-sounding on some recordings. Third, uppermost high frequencies through the T2 are just slightly subdued—a quality that some listeners might scarcely notice, but that some might find can make high frequency ambient cues or the “air” in recordings sound truncated to some degree.

On the whole, the T2 offers a warm, vibrant, and engaging sound, though one that can exhibit occasional upper midrange/lower treble rough spots in the form of the aforementioned brittle-sounding transients. Don’t get me wrong, though: the T2 is for the most part a very enjoyable monitor to use, and one that will win its fair share of hearts, minds, and ears with a sound that is, in a rather subtle way, a bit larger than life. It’s just that critical (or perhaps I should say “hyper-critical”) listeners will find some shortcomings, as noted above.

By comparison, Ultimate Ears’ IERM was and remains our reigning “neutrality” champ. In practice this means the IERM offers a smoother, more evenly balanced response curve—especially in the critical midrange-to-upper midrange and upper midrange-to-treble regions. While the T2 Classic can, in certain respects, sound more exciting to listen to, there is a certain ineffable rightness to the IERM’s midrange and high frequency tonal balance that reminds me of the sound of very costly high-accuracy monitoring loudspeakers. Some people love the sound of accurate monitors, while others might prefer the warmer, more vibrant (albeit somewhat more colored) sound of the T2 Classics.

Down low, the IERMs just plain have less bass (or at least less overt mid-bass) than the T2s, though I think those who know and love bass instruments will find the IERMs are actually truer to sound of the real thing. This is an area where I realize many listeners prefer a hint of elevated mid-bass, which is precisely what the T2 offers. The IERMs, in contrast, offer what is arguably a more fundamentally natural and realistic bass sound, but one that—for better or worse—gives listeners only as much bass output as is provided in the original recording.

Finally, the IERMs deliver an extra—and I would argue accurate—measure of high frequency extension and air that the T2s cannot quite match. As I mentioned above, this is a relatively small and subtle difference that some listeners might not notice at all, but that others might. It’s a difference that gives the IERM a small edge in terms of conveying an overall sense of the acoustics of the original recording space.