With most of the other amplifiers I’ve tried, including the Beta22, the Grace and the Burson HA-160, I didn’t quite feel the magic of the HE5LE. One of the aspect that makes the HE5LE un-involving on those amps is the midrange to lower treble which doesn’t have enough presence for vocals. Although the technicalities are very good, but without a good vocal presence, music becomes dull and un-involving.
The EF5 amplifier changes that. In stock form, the amplifier is very warm and mellow, with very thick midrange and low end body. The soundstage image is very good, and more than what I expected from an amplifier at this price range. It’s not nearly as big as the solid state I’m used to listening, but it has a very coherent and unified soundstage. There is a circular sphere where the music takes place, and if I struggle to get a good soundstage coherence from the other amps, with the EF5, the HE5/LE really gives a nice soundstage. The EF5 is more of a mellow sounding amp than a lively/energetic one. Pairing the EF5 with the HD800, for instance, makes me feel that the overall sound is too mellow, lacking pace and attack. The HE5/LEs are quite an agressive sounding headphone, however, and with the EF5, the combination is just perfect, as the EF5 has a smoothing effect on the lower treble and midrange, and that works well to smooth out the treble area of the HE5/LE. The HE5LE also gained a fuller sounding upper midrange, which I think is precisely what the HE5LE need to shine. I haven’t been listening to the HE5LE for a long time, but with the EF5, I’m rediscovering this headphone once again.
Part of the synergy is also the HRT Music Streamer II+, which I feel to have a superb synergy with the HE5LE’s sound signature. On the other DACs that I’ve been reviewing, I felt that the HE5LE needs to sound more engaging, the way the original HE5 is. The Music Streamer II+ does have an energetic sound presentation that creates the perfect signal for the HE5LE. I’ve always wanted the HE5LE to be a little more agressive like the original HE5, but I can’t stand the bright HE5 presentation. Now with the MSII+ DAC, I’m getting a lively sounding HE5LE but without the brightness of the original HE5.
Although the synergy of the EF5 to the HE5 & HE5LE is great, it doesn’t limit the EF5 to be used only with the Hifiman headphones. The EF5 in general smooths out any harsh treble and adds a good midrange and low end body, and is quite a good match if you think your headphone’s treble is a bit too agressive and/or you feel like you need more midrange and bottom end body. I’ve tried the EF5 with the Sennheiser HD800, the Beyerdynamic T1, the HE5 and the HE5LE, and I think the EF5 is a good match for all of those except for the HD800, where the sound gets too mellow.