Pros: The amazing sound!, high rez file support, quick and straight to the point UI, buttons and analog volume control wheel.
Cons: Slightly bulky (2x thick than ipod), average battery life, buggy firmware, file and sd card support is sometimes random and problematic, slight hiss.
"The packaging was very boutique. It demonstrated the fact that head direct is a small company. The pleather box it came in had the bottom falling apart due to the glue unsticking, but it was an easy fix. It came with a chinese power adaptor with a US plug (which means I had to buy yet another because I live in aus). Charging took 2 to 3 hours. It also comes with a microfibre cloth, and decent length usb cable and a velvet bag with strings you pull to close the opening. The hifiman itself was chunky and had a plastic feel to it, but the size was very reasonable. The plastic casing around the directional buttons is raised, which at first annoyed me until I realized how handy it was for preventing accidental button presses.
The sound is #$&@#% amazing!! When people described it as musical I didn't really know what they meant, but for me it's simply a cleaner, more original (real/analog, etc) sound. The hiss originally bothered me a little bit but when listening to music at a comfortable level you cease to hear it. Again, the sq is what I bought it for and it really delivers. I am absolutely satisfied with it. Not being able to play anything but audio is great too, because it meant I can save room by deleting album art and m3u files, etc.
I experimented a lot with the hi/low gain switch, and noticed that only the bass and details emerged and the volume stayed roughly at the same level with everything else. I usually keep it on high gain with my Westone 4's and leave it at 2 or 3 on the volume control (btw, having an analog volume control wheel is awesome, i love it). With my BeyerDynamic DT770Pros 250 Ohm, the bass and mids are delightful and the volume can be maxed without being painfully loud. You can feel the air move with each bass note, a very different feel to the bass of the Westone 4 iems.
There is absolutely no gapless, not even close. Listening to Cat Power's 'Jukebox' album (192kps) there was a hiss present through out the track, and when it came to the end of the track and the start of the next, all sound (including the hiss) disappeared for up to a second before the hiss kicked in again and the music started. This doesn't bother me much, but it apparently does for other people, as the lengthy threads have documented.
I have some high-resolution (24bit) Chesky Reference albums that I put on the sd card (SanDisk 32gb, class 2) that would simply refuse to play. The whole UI would lag and react strangely, teleporting through folders and not playing anything. This doesn't apply to all 24bit music. My greatest sounding recording is Frank Sinatra's 'Sinatra's Sinatra' album. I usually use the first track, 'I've Got You Under My Skin', which is 24bit/96khz (2962bitrate) flac. Frank's voice sounds beautiful, real and there and right in the centre of your head. It almost feels like you're singing. The high hat has lovely delay and detail, the bass is tight and accurate, the instrument separation shines with the brass, woodwind and string instruments. Everything is clear and the recording has been beautifully mastered (I feel like I'm running out of accurate adjectives to describe these qualities). 2 and a half minutes into the track there's an instrumental interlude, and I swear I could pinpoint EXACTLY where the musicians were standing in respect to me. The trumpet was exactly a metre behind and to the right of me. It felt incredible.
I also auditioned New Order, Blue Oyster Cult, Chopin's Ballades (by an unknown pianist - nb: i could hear their every breath as well as every emotional nuance of the piano), Death, Echo & the Bunnymen, Joy Division, John Coltrane, Deftones, Megadeth, Mozart, The Smiths, Burzum and Fever Ray amongst others. I won't go into details of each one, but the hifiman performed every genre admirably.
The battery lasted 5 days for me before I had to recharge it. I listened to it as I was travelling from location to location (eg, work to home, home to music store, etc), so I'm quite happy with the battery life.
The UI is normally quick and easy to use. Navigation is a breeze but it does lag when it attempts to play incompatible high resolution files.
My class 2 Sandisk SDHC is a pain in the arse to load up, as the transfer speed is shockingly slow (alas, it was cheap) and on every boot I have to reinsert it, which I don't mind because it satisfies my mild OCD.
I let a few people listen to it (partner and friends, one of which is a sound engineer). Received quite a few reactions of closed eyes and smiles, and tapping feet, etc. I myself experienced aural orgasm when I first listened to it, the music really excited me and I reacted emotionally which is great for a portable player. My sound engineer friend commented that he could hear the whole mix of the demo tracks clearly on the hifiman.
Overall, very happy. Best purchase I've made this year."
Impressions quoted from forum post: http://www.head-fi.org/forum/thread/524012/review-hifiman-hm-601/765