Another new user here. I am using mine with ATH IM-04. I auditioned it against Pico slim, ALO Audio RX MK2, ALO international and Matrix Mini portable amp. Here's my amateur review.
The Matrix was the darkest amp but good bass impact and body and the sound was thick. Big soundstage and imaging was good with depth. Unfortunately, playing with the equaliser settings was not solving the darkness issue. On some songs, it sounded as if they were as a veil covering the higher frequencies. Also output impedance was 13ohm whereas the IM-04 is 14ohms impedance. Didn't have the sweet lushness I was looking for which made me fall in love with the LCD-2/v200 pairing (my desktop rig).
The ALO Audio mk2 was a step up. Good bass impact, soundstage and imaging. Got me toe-tapping right away. Not dark like the Matrix but slightly on the warm side. This was a used unit so I wasn't sure how much burn in it had, but it sounded good. But no USB charging and I didn't like the volume control and it didn't come with any warranty from the shop.
Pico Slim. A little more laid back/smooth presentation, slightly smaller soundstage and less bass impact than the rest. Reminded me a lot of V200 that I own, transparent and the music just flows. Good functionality with it being super small, long battery life, USB charging and super basic to use. Definitely a winner. But only good for iems as it lacked power for the full cans.
ALO international, I listened for about 10 sec. I am sure it is a good amp, but not for me. It felt too dark after listening to the Pico Slim. So I gave up on it right away and put the Pico Slim back on.
So, I decided to get the Pico Slim. As I stood up to get my wallet out of my back pocket, my eyes fell upon a white box in a nearby glass cabinet with the lettering Apex Glacier written on it. I enquired if it was a new unit which it was and then decided to plug it in. First impressions were not favourable. It felt a bit harsh (I was not expecting and use to the forwardness) but it had more bass impact and details than the Pico. Soundstage was slightly bigger too. So, I plugged the Pico back in. Smooth sound once again. Listened to it for a while and then put the Glacier back on again. The Glacier was a little more detailed and the texture/tone of guitars and drums was just too good to be ignored.
After doing a few more A-B comparisons. I went away for dinner to think it over and then came back. End of the day, I wanted the most natural sound with good bass impact and made me feel the music. I thought the Glacier matched well the IM-04 (These iems are on the warm side and smooth to listen to with good details and mid bass hump which gives good impact. Soundstage is pretty big for iems and the imaging is spot on with good depth).
The Glacier's well implemented design, flexibility to use different phones and built in DAC sealed it. Definitely a match that comes close to the V200/LCD-2 combo. The shop (Dontblameyourears.com) only had one Apex Glacier remaining and gave me the amp for $375 including a Fiio Silver cable. I enjoy spending time in this shop and they really look after their customers btw.
