IEM amps?

What do you look for in an IEM amp as opposed to amps for full sized headphones?

 

Noise floor, hiss, etc. at the low gain level. The quieter the background, the better. Also, turning the volume knob shouldn't go from 60dB to 80dB after a 10 degrees turn. Portability important too, since IEMs will be traveling with me.

 

Low output z (z<1) is an absolute must. Battery life should be long (>8 hr). No hiss at any given volume. A high/low switch for relatively inefficient IEMs like ATH IM04 would be good but not necessary. Ability to drive UERM with extreme delicacy would be a huge plus. Preferably without a DAC built in.

 

All of the above plus channel balance.

I previously owned a Headamp Pico Slim and it was a pretty much perfect for IEMs. Battery life was ~50 hours too. I didn't have it at the same time as my UERM though...

With IEMs I think the transducers make up even more of the equation than with headphones. Most IEMs sound pretty good out of my iPhone. As long as the above conditions are met, you are chasing 5% or so by adding an amp for portable listening. IMHO, YMMV etc.

(There is no science here, 5% is a random number chosen to illustrate a marginal improvement).

 

All good points, you'll also want small enough to lug it around. Pico slim is one of the best around, probably the best all rounder for all requirements above, then you'll have Leckerton uha-6s which are not as small nor light and discontinued unfortunately, vorzuge is good but pricey, that's from the top of my head.

 

The Slim certainly is small...

 

For exclusive IEM usage, I would recommend the Alo Audio RX IEM. It won't drive anything else other than your most efficient headphones, but for IEMs, noise floor is low, no hiss, little coloration, just very clean.

The Pico Slim is very good as well, but I owned it too long ago to make any responsible comparisons. Form factor is incredible, much lower physical footprint than the RX.

 

Have to agree with muse on the Rx, especially on the cleanliness. I especially like that it doesn't provide an artificially cavernous soundstage by inducing "echoes" like the fiio x5 in-built amp, but with the clarity it provides, the soundstage by no means sounds small. Own one myself, and used it very frequently till I lost my IEMS (damn!) And yes, since it's the new Rx, that wasn't very long, but I enjoyed every moment while it lasted. For now it's stuck in my drybox till I have saved up enough and found a CIEM that I really like. On the plus side, this has freed up my commuting for reading, which I have missed out on for a year.

 

I totally agree with this. Not only because IEMs tend to have much lower impedance but also because the higher end ones have multiple drivers and crossovers which will lead to more interactions with a high output impedance.

That's a bit what I was thinking. Adding an amp to a system that is made to be super portable will make it a bit less portable. For me a bigger reason to get an IEM amp is more for functionality, like analog volume controls or using the lineout of the dac section to connect to a HiFi system.

Sometimes I think of it a bit like the Schiit Wyrd. Great if you have a bunch of line noise but might not make any difference if the USB is already low noise. Well a lot of laptops have headphone outputs with +20 ohm output impedance and need an amp to get a low impedance output. But smart phones largely do pretty well powering IEMs and you'll probably just be chasing an extra 1%.

 

if you could score a used alo national plus (avoid the national due to its 20 ohm ZO) or the cypher labs picollo... both are compact (smaller the alo rx) fully discrete amps that provides both gain and attentuation (-11db) and <1 ohm ZO, and lasts 20+ hours. i really liked either with very sensitive iems. National+ is more meaty and intimate, whereas the picollo is a little more on the smooth side of neutral with perhaps more air.

(use google translate)
http://av.watch.impress.co.jp/docs/review/review/692351.html

i preferred the level of "play" their volume knobs have over the newer Rx, and ime, hisses even less. Rx is sonically in between the National+ and Picollo but iirc has more gain than needed.

note that both products have the dreaded turn on pop and some pot scratching...

 

The Leckerton UHA-6S MKII (w/ AD4627B opamps) is still a favorite of mine for IEMs (and efficient cans).. it's a Chang/SBAF certified amp for driving IEMs. Mad clean sound.. scales damn well with DACs..and you can get the gain dropped (if the stock gain settings are too high). I've owned it no fewer than three times.. and am thinking about getting it again. Beautiful sounding amp.. really well built. Meier Audio QuickStep2 gets a recco from me as well, up there with the UHA.