There were many players used for testing of Heir Audio 10.A. From classic Sansa Clip Zip over Fiio players to high-end Calyx M and Hifiman HM901S. Even though Heir sounded wonderfully even from basic Clip, each step up in players was clear improvement. IEMs of this category really deserve appropriate portable rig, so investment into some dedicated Hi-fi player is worth it.
When many other IEMs try to impress on first listen with one particular range, Heir 10.A is more about whole presentation. They are little bit mid-focused, but no part of sound is too enhanced or suppressed. Thanks to that, they sound balanced and natural. They are great mix of extremely clean sound with ton of details with pleasant and engaging sound, that will keep you wanting to listen for many hours. Bass has great impact, sounding full and strong when needed. Yet it’s never too much and bass never bleed into midrange. There is no enhanced mid-bass and Heir are really truthful to recording in quantity of bass.
Really good are technical aspects of bass, great control and speed, that surpass almost all IEMs I tried. Not even my old JH Audio 16 with 4 bass drivers couldn’t catch up sometimes. Great bass extension and little bit enhanced sub-bass adds fullness to instruments and offer great rumble needed for classical and movie music. Many other BA based IEMs has problem with this and it’s one of reasons we see more hybrid IEMs lately. But Heir 10.A manage it great with just two balanced armature drivers, probably biggest that you can get from Knowles. If bass was great, midrange, strongest aspect of Heir 10.A, is just amazing! It’s little elevated and adds slightly warmer tone for more pleasing sound. Voices and instruments sounds full, alive and engaging, they really draw you into the music. Even though there is warmer tone, Heir 10.A offers great clarity and amazing detail, surpassing most IEMs on market. Highs are balanced between enhanced, energetic and smooth. They are not harsh and don’t sound artificially, they go really high with great clarity and with enough air. They might be little bit strange in the beginning, if you go to Heir from brighter or darker earphones. I myself always preferred brighter sound and I needed to adjust to more relaxed highs of Heir 10.A As many other customs, Heir has great presentation of space. Soundstage is large, but main advantage of these lies in localization. Each instrument has it’s own place, strictly separated from others. It’s easy to locate it not just in direction, but also in depth of soundstage. I always use song This is Halloween from the movie The Nightmare before Christmas and no other IEMs I tried managed it complicated soundstage as good as Heir 10.A.
Heir 10.A are not for bassheads, neither for people looking for cleanest analytical sound. They don’t offer huge coloration and their highs are not super sharp. They are simply really pleasing, natural and fun IEMs. And you will enjoy them everyday. I had few high-end universal and custom IEMs in past, but non of them managed to offer so clean and controled sound with so natural and fun presentation. For me, Heir 10.A are simply the best IEMs I ever heard. If you are interested enough in portable audio, Heir 10.A gets my highest recommendation. You will not be disappointed.