[revault]

I'm looking for a portable amp that I can hopefully stuff in my pocket along with my source component (usually an iPod with a LOD cable). I've listened to cheap little cmoy tin amps, and they're pretty nice except they pick up a lot of EMI when I place them on my desk (which is also common). Headphones I use range from fairly easy to drive 50 ohm ones to some 600 ohm cans like oldschool AKG K240s.
 
I'd like the usual 3.5mm I/O, an indicator LED, and maybe the volume knob as a switch (although the lack of that wouldn't be a deal breaker). 
Any recommendations?

 

[Ap616]

The GemTune WS1.2 BlueBird is a great sub-50 portable amp, so is the Topping NX1. I have both! They are powerful and small. The Topping lasts forever(like 100+ hrs), but I like the clean and seemingly less fatiguing sound of the GemTune. Though the NX1 sounds clean too. They are about the same size in length and width, but the Gemtune is twice as deep while still small. The Topping is tinier but powerful. The Gemtune is a little bigger and even more powerful. The NX1 has an on/off switch, HG/LG, led, volume knob, charging port; the BlueBird turns on/off when you plug/unplug the cable, has led, volume knob, charging port. They both do exhibit EMI though unless you turn you phone into airplane mode.
 
These are probably your two best under $50 options, maybe even better than a cMoy or FiiO e11($60). Hope this helps!

 

[revault]

How do you think they compare in terms of build quality?

 

[Ap616]

How do you think they compare in terms of build quality?

They both seem really solidly built so I don't think you'll have any problems there, unlike a plastic FiiO or tin cMoy. Both have a premium, HQ feeling with their metal casings/design. The GemTune might have a slight edge in quality and is twice as deep to boot.
The NX1 has better battery life and a very slight v-shaped sound, while balanced and clean sounding. The GemTune has slightly boosted lows like the NX1, but instead of going for the slight v-shape, it brings out the mids more by slightly boosting them too... giving a little warm/smoother but still really clean sound as well. Both increase details, soundstage, and overall speed of an iem or headphone fairly well in my experience. And they both sound flat & balanced and these signatures aren't too noticeable IMO.
Here's some pictures for comparison of build and size:

 

[revault]

I'm considering buying the NX1, there's a lot of good feedback about it here. Someone did frequency response measurements and the NX1 seemed to measure nearly ruler-flat. Judging from the feedback I think either seems like a very decent choice. Where'd you order/buy the NX1?

 

[Ap616]

I'm considering buying the NX1, there's a lot of good feedback about it here. Someone did frequency response measurements and the NX1 seemed to measure nearly ruler-flat. Judging from the feedback I think either seems like a very decent choice. Where'd you order/buy the NX1?

Yeah, they are both good choices probably. I like the little less known one that fits my preference a little bit more
Yeah, it had flat measurements and mostly sounds clean and balanced, but it is just very slightly v-shaped sounding according to others & my own listening.
Um, where are you from? US

 

[revault]

Yeah, US. 

 

[Ap616]

Yeah, US. 

You can get it at Amazon for $43, which is where I got mine. Or you can order from here for about $33(the brand new DXsoul directly to the US website; DX also has it too...): http://www.dxsoul.com/product/topping-nx1-headphone-amplifier-for-mp3-mp4-cellphone-tablet-pc-black-901294594#.U-o0VM8o4m8

Also, someone was saying they offer a lot of coupons/discounts for new customers I think so maybe search for those first idk. That person ordered the TTPOD T1-E and NX1 from there a day or two ago.