These are really exceptional little units, particularly when used in balanced mode and with the Apple CCK USB3 cable (the USB2 CCK sounds worse). The included micro-USB cable actually sounds quite good and uses quality Teflon gold-plated connectors, and is as good or better than my Anker Powerline+ Micro-USB cable. (And I’m a cable builder and could build better ones but for portable use these are fine.) I prefer the included cable as it’s much more flexible than the Anker.
My main issue with these units are the cheaply-made plastic buttons which have HORRIBLE QUALITY! The MK1 had far superior buttons that didn’t rattle or have poor touch response. Fortunately the only button you really need is the power button as all others can be controlled through their app and your music player app. What makes this device great is their amazing EarStudio app which has so many features and is far superior to any other company’s app. The battery life is also very good.
The other problem with this unit is that you need to switch it to “self powered mode” when using it with OTG interface for iOS or Android. This means you cannot charge it simultaneously while using it though with the Apple USB3 CCK you can charge your iPhone (and if you do, use a power bank so it’s all DC power; using a USB wall adapter can introduce noise). But the main problem with the self powered mode is a bug in the ES100 hardware where sometimes after you disconnect it from the cable it will not power on via the power button unless you first plug it into a charger, and I have no idea why they haven’t fixed this yet since I’ve only told them about it over 100 times so far.
But for the price it’s absolutely unbeatable! I use it with my $2,500 Audeze LCDi4 and they sound great. The setup is as follows:
• iPhone XS Max > Apple USB3 CCK > RadSone included Micro-USB cable > RadSone ES100MK2 or MK1 > 2.5mm-to-XLR4 female > Audeze’s $400 included cable with the LCDi4 (but I had them terminate it with an XLR4 male connector) > Audeze LCDi4
Another much less expensive setup that sounds incredible (with one of the best sounding pair of $150 headphones I’ve heard, the HD598) which includes the ES100MK2 and other cables listed below that I bought for a family member for Xmas, who already has a Sennheiser HD598, uses the following (and he hasn’t heard it yet, though I have tested it, as he’s only used to using the puny $9 Apple Lightning-to-3.5mm adapter, so he’ll truly be blown away:
• iPhone 6 Plus > Apple USB3 CCK > RadSone included Micro-USB cable > RadSone ES100MK2 > custom made OFC balanced 2.5mm-to-Sennheiser HD598 proprietary connector (bought on eBay for $21) > Sennheiser HD598.
This is also an exceptional sounding Bluetooth 5.0 unit! You can hook it up to your home receiver via a 3.5mm-to-RCA and stream lossless music via AAC, aptX, and even LDAC if your Android device supports it.
I don’t know of any other $100 device ($85 here) that can do what this 9V battery-size unit can do (yes, it really is that small and thin if you were to remove the clip), combined with its AMAZING app with infinite controls, so for $85 it’s a real steal! (I have never tried their HE100 IEMs but they seem to have good reviews and might be worth acquiring for the additional $55 as they are normally $89 and are meant to pair with the ES100, though for reasons beyond my understanding they did not make the HE100 with a 2.5mm balanced cable!! They certainly should have as the ES100 supports it, and could have included a 3.5mm adapter for those who don’t want to use the ES100MK2.)
I’m not particularly fond of the microphone quality, but that’s just a minor inconvenience for a device that does so much.
I personally prefer everything about the MK1 as it has all the same internals and the opaque cover that conceals the bright RGB LED; all it needed was the new clip featured on the MK2 for those 5% of people who are even going to use the clip. If I had designed it there would be no clip.
Don’t be hesitant about the purchase; just beware about the cheap buttons that often don’t work: I’ve tried 4 units and they all have this issue whereas the MK1 did not.
Note: I am in no way affiliated with this company and my opinions are my own. I have shared my concerns with RadSone and have given them suggestions on how to fix this unit as well as improvements for a MK3 unit. I have not been compensated in any way by the company; I did receive a replacement unit from Amazon since it was missing from Amazon’s torn box the first time, as well as a promo code from RadSone for a replacement unit but they both have faulty buttons, and so do my friends’ units (so be prepared to receive it with rattling, faulty buttons on at least one side of the device that work poorly: either it will be the volume button, the track button, or both – fortunately this can be overcome by using the buttons on your phone).
Still, even with those issues the unit is a great value and I suggest you download the EarStudio app and look at all its features before purchasing so you can see everything you will be able to do with the ES100MK2. The app alone was what finally convinced me to purchase it!