Headphone Amplifier DAC Portable Amp - HiFi Audio USB Earphone Amp Decoder ES9028Q2M XMOS XU208, Support 16-600Ω Earphone 32bit/192KHz DSD256 with Bass Boost and Gain Switch for Phone Laptops PC MP3

This is an excellent portable amp for your phone! It definitely gave headphones a cleaner sound and also really helped power headphones with high impedances. I have the Fostex T50rp Mk3 which need quite a bit of power to work and this did a pretty good job at it.Another thing I like about this is that it is built very well, everything feels solid and I don't worry about this breaking anytime soon. It's very sleek and small and doesn't make your phone too bulky. The volume control and ports are placed nicely as well.The battery life is rediculously good. I couldn't believe how long this thing lasts! Also I thought the price for this was very good for what you get.I would have liked to have seen better cables however. The mini aux cable that comes with it is very cheap and doesn't work very well.

Sound and DAC were perfect, but it can be interfered by a phone (Makes noise when there's a phone near it.)

Overall this thing is pretty much unbeatable at this price and this size. I've been using a C&C BK for the past 4 or so years and to be honest I still prefer its sound, but it does not function as a DAC and, truth be told, I'm probably just used to its sound. The NX2 is less coloring to the music, a more "clinical" sort of sound, which is far better than too much color if I had to choose.Some of the best listening I've ever had is plugged into my Lenovo using the NX2 as DAC and jumping that to the C&C and out to a pair of Triple.fi-10 IEMs. Pretty effing spectacular, really. I get the noise free accuracy of the NX2's DAC and the extra warmth and punch from the BK. Obviously that's slight overkill. :) Or is it?Anyhow - I don't go around with two headphone amps. I would say the NX2's amp fuction is a bit warmer and more "sparkly" possibly due to the high roll-off in the DAC stage another reviewer mentioned. Not that big of a deal - it sounds great. Beats the pants of the noisy and *extremely* inference-prone DAC onboard on my laptop. In comparison the NX2 is utterly SILENT during song pauses, to the point it was disconcerting because I'd gotten so used to hearing a bit of "running noise" as it were with this dang laptop.The amp stage sounds great, a bit better I'd say, but I've not listened nearly as much that way and honestly I'd still pick up my BK 50% of the time ... but the battery does last longer with the NX2 and it's thinner.... Though it is slightly wider and longer than the BK, the fact that its roughly the size of a credit card but is thinner than the girth of a pencil, it's just as, if not a bit *more* pocket friendly.Great little amp/DAC. I was gonna spring a bit more for the new FiiO Q1.... I'm glad I didn't.

Unfortunately, my unit had a bad power switch and did not like to stay on even after a sufficient charging period. I do not see many people with this problem so I will not give the product one star as the bad switch seems to be an anomalous experience. If I fiddled with the switch and held it still I could get the power to stay on and I can say the battery lasted as advertised and sound to my ATH-M40x headphones from S7 Edge and ancient desktop at work was much improved. I'm not a huge fan of the loose volume wheel nor the pokey power switch so I will likely try a FiiO or SMSL product next.I will, however, recommend purchasing this item from a different seller. The unit had the problem out of the box and I contacted the company for advice. They asked me to make a YouTube video of the problem (a first for me) and I complied, only to not hear from them again. I made several Amazon-confirmed attempts at contacting them for a week and received no word back.Thankfully, Amazon made my return painless and made funds available for me to get another DAC amp on the same day. I'm truly impressed by this.

I have been using this with my Sennheiser HD 598, and it's a big improvement over my laptops 3.5mm out. They were already loud enough with the onboard sound, but the NX2 improves clarity, especially at lower volumes, and I think there's better bass response than I was getting before too.The unit came partially charged, and plugging it in with the included micro USB to USB cable triggered an automatic driver install in Windows. You can then select the DAC as the audio output in the Volume Mixer.The build quality (especially metal body) is pretty impressive for the price, although the power switch and volume dial do have a little wobble to them.

Less power than my cellphone and TONS of static. Must use in airplane mode with my phone.

Did add headroom. Quality was not much better then my Galaxy S4. Not worth it in my opinion.

Nice little Amp. Be mindful that this unit is AMPLIFIER only! If you need a amp/dac combo this is not the one. It is a great amp and definitely boosts the volume for my headphones that need a little more push. Most smart phones have their dacs onboard, so increased volume may be all you need. Two thumbs up for this amp with the super battery!!!