DAP with the best sound quality using Rockbox and IEMs?

[woodensoul]

Since receiving my Shure SE210 IEM earphones, I've been hearing a lot more than I ever had before, and that includes instruments and dynamics in the music, but unfortunately hiss, hard drives spinning and insanely weird electronic noises as well.

The point of this post is to share what I have observed using IEMs with my Rockboxed DAPs and to get feedback from those of you who have IEMs and have used players other than those in my list.  Which player sounds the best?

iPod Video 80GB - best of the ones I've heard for these reasons:  no hard drive spin-up noise, and very, very little hiss

Gigabeat F - 2nd for small amount of hiss, but hard drive noises come through on spin-up

iRiver H100 & H300 series - 3rd for most hiss, but no hard drive spin-up noise

Sansa e200 - last for the hiss and insanely annoying electronic noises that come through on buffer refill

What's your experience?

[markun]

I have the same experience with the iriver h100 and Gigabeat F. Don't own any other rockbox targets yet.

[soap]

iPod has trouble driving low-impedance loads (sub 48 (sub 32 very much so) (and most IEMs are 16) .  Causes significant bass-rolloff.  (Your Shures are @ 21ohms, though - will have much less rolloff than others - you can RMAA this yourself.)
iPod has trouble driving high-impedance loads (>~100) with adequate power.
Can't speak to the other players (thought the bass issues are a trademark iPod curse).  For better or worse the iPod is simply better "documented" by the greater internet community.

Infact - strongly suggest you look for RMAA tests on all the players you are considering.  RMAA tests done under load.  There is a large percentage of the population who believes all sort of wacky theories things which just aren't objectively true.  Opinions on perceptual audio merits are like mushrooms.

[frause]

I'd say the iaudio M5. It does not have the hiss of the irivers or the low impedance problem of the ipod(s?). Since I don't own one, I don't know about the X5 but I imagine it sounds the same.

[ZincAlloy]

hiss? what hiss? my h300 isn't hissy at all.

[Llorean]

The H100 and H300 are most definitely hissy. If you don't hear it, it's most likely an issue of what headphones you're using.

[ZincAlloy]

I use Koss Porta Pro headphones.

[Llorean]

Yes, you probably won't hear it with those. It shows up most evidently in IEMs where you're listening at much lower volumes.

[Lear]

The H100 and H300 are most definitely hissy. If you don't hear it, it's most likely an issue of what headphones you're using.

Different headphones have different sensitivity (and impedance, if that makes any difference for this). I've tried a couple of different in-ear headphones with my H100, and the more sensitive ones do pick up the hiss. With one set of headphones (104 dB sensitivity, 48 Ohm impedance), there's practically no hiss at all.

[ZincAlloy]

my porta pros are have a sensitivity of 101 dB SPL/1mW with an impedance of 60 Ohm.

[Llorean]

Are you asking anything? I've already said you won't hear it with those.

[Christine Tham]

If you are truly interested in choosing based on objective sound quality rather than perceptions (unfortunately our ears cannot be easily trusted since they are quite adaptive), I second the recommendation to conduct RMAA tests. They are relatively easy to do, but require a PC with a reasonably good sound card, preferably a pro-audio sound card (but reasonably good ones start at around US$100).

However, RMAA doesn't tell the whole story. In my experience, jitter is a significant influencer in overall sound quality.

Unfortunately:
1. Jitter is not easy to measure. Some commercial test units are based on the J-test methodology proposed by the (late) Julian Dunn. Since the J-test does not actually measure jitter but artefacts potentially caused by jitter on a specific test waveform, some skeptics say it is not a true measure of jitter.
2. I suspect most portable players have poor jitter. I don't know if one player is better than another. John Atkinson has measured the jitter level on the original Ipod using a Miller test unit, and the results weren't that good (as I recall, several times higher than a good cd player).

My recommendation is to choose the top 3 players based on RMAA, then conduct extended listening tests to determine which one your ears prefer. Perceptually, the influence of jitter is on the "pace, rhythm and timing" of the music (PRaT). Have you ever wondered why some players sound more exciting and aggressive, others tend to sound laidback and relaxed ...? On some players, the drummer sounds precise and tight, on others a bit wooly? Even though the actual tempo is the same, our ears pick up other clues to determine our emotional response to music.

[Llorean]

I hate to be pedantic here, but while trying to describe an objective issue, you've been very subjective in what jitter results in. As well. jitter in CD reading is often an issue with the actual reading. What phase are you particularly concerned with jitter in, communication with the DAC?

All you've done is basically said "jitter makes it sound bad." Where, exactly, would jitter occur on an MP3 player, and how much, exactly, is the maximum it could reasonably be expected to affect output in hard terms?

[Febs]

Do we really want to get into discussions here about whether jitter is audible?

[Llorean]

I was looking more for some math. Average percentage of lost and/or repeated samples, for example.