Synergy between Portable Amps and IEMs - 9 IEM compared with 9 portable amps = 81 chances to mess up!
Jun 26, 2008 at 9:19 AM Thread Starter Post #1 of 83


Headphoneus Supremus
Aug 18, 2007
[See the end for an update on 8/2/08]

PROLOGUE: The other day I was re-listening to the 5 pro that I originally got for my daughter, which she had traded back to me for my JVC FX66 Air Cushions. The sounded much worse than I remembered from the last time I listened. I observed that I was using them with my Meier HeadSix instead of my RSA Predator as usual. Normally I often enjoy the HeadSix with my Denon C700 or Livewires, but the really sounded bad this time.

I switched back to the Predator and the sounded fairly decent, so I decided to try all my other portable amps with the 5 pro (except not the TTVJ millet Hybrid Portable as the gain is not adjustable and the channel imbalance at low volumes is an issue with sensitive IEM). Anyways, I found that I disliked the 5 Pro with just about anything but the Predator, re-affirming why I sold my first pair of 5 Pro last year. But, the HeadSix was actually the worst of the seven amps that I tried with the 5 Pro. That makes no sense to me, considering that the HeadSix is an amp that I really enjoy with the Denon AH-C700.

It occurred to me that many of the opposing viewpoints in regards to a particular amp or IEM may be due to the presence of synergy between the two, or lack thereof. So, I tried out 49 different combinations of 7 different portable amps with 7 in ear monitors (IEM), including 3 custom monitors and 4 universal fit models. Some of the results were eye opening, especially that two amps with similar sound signature or ranked a certain way with one particular IEM do not always rank the same with the next IEM. Also, the ranking with some full size headphones doesn't always translate over to the ranking with IEMs - in my case my ears are more sensitive to when something sounds "wrong" with IEMs. All of this implies to me that an amp's sound signature (or performance with certain full size headphones) alone is not a reliable predictor of which amp will work best with a particular IEM.

IEM TESTED (in order of best to last in sound quality - all fully burned-in):

1. Livewires - two driver customs
2. Freq Show - three driver customs
3. SE530 - three drivers in custom acrylic shell (totally different sound vs universal with slightly less bass but more treble extension)
4. q-JAYs - 2 driver universal
5. IM716 de-podded with 47ohm resistor - single driver universal
6. Denon C700 - single dynamic driver
7. 5 Pro - two driver universal

PORTABLE AMPS TESTED (the rank depends on the IEM - all fully burned-in):

1. RSA Predator
2. Headamp Pico
3. iBasso D2, modded with LM6172/THS4032
4. Headroom Micro Amp
5. Headstage Lyrix Total Pro
6. Penguinamp Caffeine Pro
7. Meier HeadSix


Livewires Amp Ranking (best to last): The Livewires sounded good with any of the amps tested, but some were clearly better than others. They remind me of my APS re-cabled Grado RS-1.

1. RSA Predator
2. Headamp Pico
3. Headstage Lyrix
4. Penguinamp Caffeine
5. iBasso D2 (moves up to 2nd if the LM6172 is replaced with an ISL55002)
6. Meier HeadSix
7. Headroom Micro Amp (treble became slightly piercing but still acceptable)

Freq Show Amp Ranking (best to last): The first 5 amps were the most pleasant, but I could enjoy them with any of the amps. Notice how the Headroom Micro Amp moves up from last to 3rd, just by changing to a different IEM. They are just a tiny bit more laid back than the Livewires, more like my APS re-cabled HD600, but a little quicker like an RS-2.

1. RSA Predator
2. Headamp Pico
3. Headroom Micro Amp
4. Headstage Lyrix
5. Penguinamp Caffeine
6. iBasso D2 (pronounced mids with LM6172 - moves up to 3rd if the LM6172 is replaced with an ISL55002 and leave THS4032 in the ground, moves to second with LMH6622 in the main amp)
7. Meier HeadSix (pronounced mids - didn't like too much but not too bad)

SE530 (in custom acrylic shell) Amp Ranking (best to last): Similar to the Livewires, but with a little less bass, these also seemed to sound good with all the amps, but some were clearly better than others. Notice how the D2 was near the bottom with the other two custom IEM, and now it is near the top with these, despite leaving the LM6172 in the main amp socket.

1. RSA Predator
2. iBasso D2 (with LM6172/THS4032 opamps)
3. Headamp Pico
4. Headroom Micro Amp
5. Meier HeadSix
6. Headstage Lyrix (with bass boost on moves up to third)
7. Penguinamp Caffeine (with bass boost on moves up to third)

q-JAYS Amp Ranking (best to last): The q-JAYS seem to have rolled off highs as they are pushed farther into the ear canal. A more shallow insertion allows better treble, or amplifier choice can be used to compensate. These were harder to drive than all but the IM716, but typically I did not have to switch out of low gain.

1. Headamp Pico (This stood out above other amps, helping fix some rolled off highs)
2. RSA Predator (a close second)
3. Headroom Micro Amp
4. Headstage Lyrix
5. Penguinamp Caffeine
6. iBasso D2 (pronounced mids - improved to 3rd place with ISL55002 opamp)
7. Meier HeadSix (pronounced mids and slight ringing in my ears - the only amp that sounded bad with q-JAYS)

IM716 Amp Ranking (best to last): Sound quality was not bad with any of the amps. However, these were noticeably harder to drive, and I had to run the Predator and Headroom in mid-gain, and Lyrix on high gain. Headsix really needed high gain, but I didn't open it to change the jumpers. The D2 did well in low gain, as did the Pico. From previous testing posted elsewhere, the modded D2 is the only amp that can make the IM716 sound their best at 102 ohm (I have a DanT custom pod that allows choosing 22, 33, 47, 55, 69, 80 or 102 ohm).

1. iBasso D2 (with LM6172/THS4032 opamps)
2. RSA Predator (almost tied for 1st, but D2 has very slightly better bass with these)
3. Headroom Micro Amp
4. Headamp Pico
5. Headstage Lyrix
6. Penguinamp Caffeine
7. Meier HeadSix (SQ good but really needs to be in high gain)

C700 Amp Ranking (best to last): I realized in this listening session that my C700 actually have a colored and splashy harsh treble with the wrong amp. I have previously said the C700 didn't sound good with the Tomahawk which made them harsh, but I had never bothered to try all my amps. I only like these with the Predator and Headsix, as they seem to smooth out the C700 sound a good bit. My biggest reason to have kept these is that they are my only canal-phones that make good bass without needing a tight seal, and they will allow a little ambient sound through for listening while I walk down the street or when I need to be more aware of my surroundings.

1. RSA Predator (one of only 2 amps that allowed me to enjoy the C700)
2. Meier HeadSix (the only other amp that was friendly to these IEM)
3. Headroom Micro Amp
4. Headstage Lyrix
5. Penguinamp Caffeine
6. Headamp Pico
7. iBasso D2 (this combination was particularly bad, unfortunately I did not get to try these IEM with ISL55002 opamp) 5 Pro Amp Ranking (best to last): As stated before, I do not like the very much, unless driven by the Predator. Even then they just sound too artificial/plasticky. I have tried Westone ES2 cable, and still can't find the right sound. The only tips I can use comfortably are the Complys T400. My first pair of 5 Pro were one of the first IEM that I sold off last year, as my SE310 and E4c at the time were miles ahead of them.

1. RSA Predator (the ONLY AMP to make these sound halfway decent)
2. Headamp Pico - tie with Headroom
3. Headroom Micro Amp
4. Headstage Lyrix - tie with Caffeine
5. Penguinamp Caffeine
6. iBasso D2 (with LM6172/THS4032 opamps)
7. Meier HeadSix

WHAT I THINK IT ALL MEANS: I really do believe that such a thing as synergy exists and is important. This part is important - I found that while most of the time an IEM can sound good with several amps or bad with several amps, that sometimes there is a match that makes a bad IEM sound good, or a good IEM sound bad, if used with the wrong amp. Likewise, ALL the amps in this review are nice sounding amps, yet with most of the amps it was possible to find an IEM that made the amp sound bad (i.e. 5 Pro).

I found it a lot easier to rank the IEM than the amps, based on the best sound I could squeeze from them by using them with the right amp:

1. Livewires (Predator)
2. Freq Show (Predator)
3. SE530 in custom acrylic shell (Predator)
4. q-JAYs (Pico)
5. IM716 de-podded with 47ohm resistor (D2)
6. Denon C700 (Predator)
7. 5 Pro (Predator)

However, there is no way I can give all 49 rankings, other than to say the Livewires with Predator was #1, and the with HeadSix was #49. In general, the Predator seemed to remain at or near the top more than any other amp. The Pico was almost as consistent, sounding best with the q-JAYS but bad with the C700. The HeadSix, in contrast to the Pico was the opposite, and seemed to only excel with the C700, but it was particularly bad with the q-JAYS and it stayed near the low end much of the time. The D2 could sound the best of all the amps with IM716 and the worst of all the amps with C700.

I found a way to score an amp objectively, where a lower number is better. If an amp was #1 with all 7 IEM, the best score it could get is a 7 (1x7). If an amp was last with all 7 IEM, the best score it could get is a 49 (7x7). If an amp was in 3rd place with all 7 IEM, it would get a 21 (3x7), etc... Here is what I got, from best to worst:

09 pts Predator
20 pts Pico
24 pts D2 (with ISL55002/THS4032 opamps - 3 IEM were not heard with this, so their LM6172 score was used)
26 pts Micro Amp
30 pts Lyrix
33 pts D2 (with LM6172/THS4032 opamps)
37 pts Caffeine
41 pts HeadSix

You may ask, what about the Livewires with their #7 amp, are they still better than the 2nd place Freq Show with their #1 amp? That one might be too close to call. Yet, I can say the 3rd place SE530 customs with their #7 amp was still better than the 4th place q-JAYS with their #1 amp. I can also say the 5th place IM716 with it's #1 amp would change rank and beat the q-JAYS if listening to q-JAYS with it's #6 or #7 amp. I could not make the 6th place C700 sound better than the 5th place IM716, but they could beat the q-JAYS only if I used the HeadSix with q-JAYS and my best amp with the C700. Finally, the 7th place 5 Pro could only beat the C700 if I used the Predator with them but wasn't allowed to use the Predator with the C700.

Interestingly, while the Pico beat the D2 when listening to 5 out of 7 of my IEM in this review, with my full size headphones (RS-1, HD600, HFI780, Edition 9 and Denon D2000) the Pico only beat the D2 with the D2000. I have added about 300 hours to the Pico since that review and I seem to like it more now, but Asr had already put many hours on the Pico before it became mine; so the extra 300 hours shouldn't have made it change that much. Also, with the ISL55002 opamp in the D2, it moves up in rank considerably with my favorite IEMs (those that it initially scored low with), so that is the opamp I am leaving in the D2 for now. The ISL55002/THS4032 opamp combo was still a good match for most of my full size cans before, so no big loss there. I will re-listen to the IM716 and others later with the new D2 opamps and report back whether it is still #1 with those, but for now I MUST rest my ear canals!

Update - 8/2/08 - Added Klipsch Image X10 and Sleek SA6, along with iBasso D2 Boa, TTVJ Portable Millet Hybrid and HR 2006 Micro Amp.

I no longer have the q-JAYS, so some of the comments below are from memory and having compared them to other IEM that I still have.

KLIPSCH IMAGE X10: I now place both the Klipsch and SA6 above the q-JAYS mainly for reasons of transparency and more crystal clear highs. In my rankings, the Image would be the top universal IEM, just below the Freq Shows. And from memory I would pick the Image over the 10 Pro or stock SE530 as well.

The sound signature of the Image is reminiscent of my Shure SE530 before I turned them into custom shell IEM, but for slightly more treble energy than the Shure. The q-JAYS had a similar smooth sound signature to the SE530 but with less treble than the Shure - which everyone complains is "rolled off" in the treble. But these Image have ALL the bass of the Shure, and better treble, with the same rich smooth mids. It is possible to kill the highs by pushing them into the ears too deep, and the sound balance does change as I move them further out or deeper in. Occasionally I wish they weren't quite so forward with pianos, and that affects the amps rankings with them a little. But like the Livewires, even the amp at the bottom of the list is still an acceptable match so far.

There is also a degree of transparency with the Image and my top three amps that I just couldn't achieve with the colored mid-bass of the 10 Pro. They have a timbral accuracy that allows live instruments to sound like the real thing. Like with most IEM, they still have a small soundstage that tends to stay within the head, but instrument placement on the miniature stage is impeccable. And drum solos are just breathtaking with these!

The Image are similar in the mids with the SA6 and with the Freq Show, in being a fairly forward sounding IEM. The Image have fantastic bass, which the q-JAYS came close to, but the image add a sparkly transparent smooth high end that make the q-JAYS just sound a little rolled off in the highs. Compared to the Freq Show three driver custom IEM, the Image are very similar but with more bass! That means the highs could use just a tiny bit more extension, but it is still adequate enough to get the job done. Likewise, the SA6 have a similar bass to the Freq Show, which while not as powerful as I would like was present and got the job done.

The Image are also one of the few IEM that I can use with the included silicone tips and not have itchy ear canals, so not are they slightly more transparent than the SA6 but they are much more comfortable for me. The Denon C700 canal phones also don't make my ears itch, and they don't need to be seated deeply for a seal and good bass. The Image can match the bass of the C700 but they are strikingly smoother in the mids and treble than the Denon, which have over a year of use on them and are fully burned-in.

SLEEK SA6: The SA6 have the bass+/treble++ ports in them, although I did try all the other ports as well. The SA6 at first didn't impress me, and I found that like with the q-JAYS and Image that the deeper they are inserted into the ears, the more rolled off the treble. It took quite a bit of experimenting to get the fit that would sound right, but they were never able to go deep enough to be comfortable without making my ear canals itch, unless I was willing to sacrifice some treble. For the best sound I had to use a shallow insertion that was simply not as comfortable, which made me experience a tickle and itch that made me want to push the IEM in to soothe it.

Once I had the fit set for best sound, the highs came up and were sparkly and clear, and the transparency of the IEM improved, but they just don't make enough bass to make me happy. I could be happy with the Klipsch bass. The SA6 are detailed, and neutral, with little coloration, are fairly forward in the mids and soundstage, and are not prone to sibilance. But they lack the transparency that I get from all my customs or the Klipsch Image.

With jazz the string bass has good texture and tone, and the fingers sliding on and plucking the strings are sharp and quick as is the bass. The mids are warm and smooth, and I do now have a sparkle on the highs. Very interesting. Bass is present but doesn't have quite the impact I would like with some rock. Hip Hop and Pop like Rhianna and Usher have better bass than with U2, Linkin Park, Led Zep, Stones or Beatles. I am still a jazz and new age guy at heart...


1) Predator, tied with Viper
1) iBasso D2 Viper with THS4032 in the main opamp and LM6172 in the ground channel,
2) Pico
3) Lyrix Pro tied with the
3) Caffeine Pro
4) Headamp Micro Amp 2006 version
5) iBasso D2 Boa
6) Meier HeadSix
7) TTVJ Portable Millett Hybrid (adds an edge to the upper mids that I've never heard with the TTVJ before)

Sleek SA6 Amp Ranking (best to last): Again, all the amps sounded good with the SA6, even the lowest ranked amp.

1) iBasso D2 Viper with THS4032 in the main opamp and LM6172 in the ground channel (open and spacious and not too forward, with shimmering highs)
2) Predator tied Pico (not as open and more forward, but bass is better)
2) Pico (seems to wake up the space and ambience of the SA6)
3) Headamp Micro Amp 2006 version
4) Lyrix Pro tied with the
4) Caffeine Pro
5) iBasso D2 Boa
6) TTVJ Portable Millett Hybrid (adds a nice sparkle without being too forward)
7) Meier HeadSix

At some point I will re-examine the other IEMs with the D2 Boa and TTVJ but I do not have the q-JAYS or Super .fi 5 Pro anymore.
Jun 26, 2008 at 9:20 AM Post #2 of 83
Reserved for updates.

Update 06/26/08 4:30PM

Clarification of Ranking:

Just because an amp with an IEM is ranked #6 or #7 with a particular IEM doesn't mean it sounded bad unless I specifically labeled it as such. I may have made some comments in the paragraph just before the rank list, explaining my thoughts when I ranked them, so look there for help. I think there was only one IEM that sounded good with other amps but not the HeadSix. The results are not the fault of the HeadSix.

Meier HeadSix:

The Meier HeadSix is still one of my favorite amps - I have these 7 amps because I still like them, otherwise I would have sold some of them. It was only with the q-JAYS that I didn't like the HeadSix, but with good IEM it was acceptable, including the Freq Show (while not my favorite with those it was very acceptable). It just wasn't good enough to make my least favorite IEM sound good - no surprise there. 5 Pro:

I do not have a hate for the 5 Pro. If I had not heard better than those, I would not know they didn't sound great. They sound decent and fair to me, just not great. I look for transparency and believability in an IEM. Any coloration that throws off the illusion drops the IEM's rank.

iBasso D2 and Freq Show:

I spent hours rolling opamps in my iBasso D2 today, trying to find the best sound from the Freq Show, and succeeded this afternoon. I swapped the LM6172 in the main socket for the THS4032 in the ground channel, and bingo!

At this point I find that with the LM6172 in the ground channel that several opamps in the main socket are great with the Freq, and bring out the treble the way it should be - including the THS4032, AD8397, LT1364 and ISL55002. They all sound similar with very small differences, and work well with the Freq Show - with the THS4032 being my preferred one, followed by the AD8397 and ISL55002, and last but still good was the LT1364 the smoothest but slightly rolled off treble (vs the others). I liked all these a little better than the ISL55002 main/THS4032 ground that I was using yesterday.

The stock configuration of LT1364 main, NE5532 isn't bad with the Freq Show, but removing the stock NE5532 for the LM6172 gives the D2 a little richer sound when used with the stock LT1364. 10 Pro:

I had these back in January, and they were not bad, but I had trouble with the fit because I had not discovered Complys T400 tips yet. I spent an hour making one pair of Shure black foam tips that could work with them, and they still put too much pressure on my ear canals, so I traded them for some Electrostatics (mapstec). I would still rank them at the top of the list for the Universal Fit IEM, and just below all my customs. The didn't seem to care much about the amp, but sounded good with the Predator, HeadSix, Lyrix, Caffeine and iBasso D1 that I had at the time. I didn't have the Pico, D2 or Headroom then.

Sleek and Image:

I would be willing to review loaners with all these amps. Just PM me to trade information.

Update - 7/8/08

I had dirty contacts inside my DanT switchable impedance pod on my IM716, I was getting slightly muted sound and occasional channel imbalance.

Now that I have that cleared up, I have to say I like the IM716 with podectomy a little more than the q-JAYS. Not that the q-JAYS do anything wrong, the sound is just different and I prefer the IM716 just a little more at anything from 33 - 69 ohm through my Predator or D2 viper. The bass is not as good as the q-JAYS, but the highs are a little more transparent. Amp synergy has not changed.

Update - 7/17/08

I now have the iBasso D2 Boa that will be fully burned in at 300 hours by next Wednesday and that is being added to the review too. I also have two pairs of loaner IEM coming in early next week, and two amps here at home that I forgot to include in this review.

So it will soon become 10 amps and 10 IEM when I add the Sleek SA6 and Klipsch Image X10 plus the HR Micro Amp and TTVJ Portable Millett Hybrid and iBasso D2 Boa.
Jun 26, 2008 at 9:43 AM Post #4 of 83
Interesting review, HA, thanks.

I read a interesting article recently, that got me thinking about amp impedance. I'm no techie, so I'll quote from the article, Keith Howard's IEM review in Hi Fi News July issue:
'(SF5P has)...highly variable impedances that make their frequency responses particularly sensitive to input impedance...they give of their best only when the source impedance is very low indeed: just a few ohms at most. With higher impedances...the UE will be subject to a broad boost centred on 1kHz, the 1kHz boost...being 3.5dB for a 15 ohm source resistance and 10dB for 120 ohm. These are big changes with inevitable effects on SQ'

As I said, I'm no tech head, but this would explain synergy perhaps? This is probably common knowledge btw, so apologies if this is useless info...
Jun 26, 2008 at 10:53 AM Post #5 of 83
Interesting review indeed.

I am also a firm believer on synergy, which is why I specially tuned my Little Country for AD700 to get maximum soundstage. It turns out it also works very well with A8, but not much so as to my other 'phones.
Jun 26, 2008 at 10:56 AM Post #6 of 83
yeah very interesting review! the predator is really a good small portable amp!
Jun 26, 2008 at 12:08 PM Post #7 of 83
that's Amp Buyer's Guide 2008 right there folks.

woulda loved it if you had some triple fis in there for testing =s
Jun 26, 2008 at 12:21 PM Post #8 of 83

Originally Posted by athenaesword /img/forum/go_quote.gif
that's Amp Buyer's Guide 2008 right there folks.

woulda loved it if you had some triple fis in there for testing =s

Second that. Also Sleek and Images. I think with all that work and research, would you be willing to test the Image, Sleek and Triples if some of us offered to loan you these IEMS?? I say this only because these three seem to be highly popular lately, receiving lots of threads on these forums.

I'd be glad to loan you my Sleeks and Images if you're interested. PM me with address if interested
Jun 26, 2008 at 1:49 PM Post #9 of 83

Originally Posted by tnmike1 /img/forum/go_quote.gif
Second that. Also Sleek and Images. I think with all that work and research, would you be willing to test the Image, Sleek and Triples if some of us offered to loan you these IEMS?? I say this only because these three seem to be highly popular lately, receiving lots of threads on these forums.

I'd be glad to loan you my Sleeks and Images if you're interested. PM me with address if interested

that's a great offer mike!

@ HA, too bad i'm too far away to lend you my trips heh. (which i'm secretly thankful for since i'm still at the "gotta listen to em everyday " part). I do hope you'll update if you have the opportunity to test them though. i was thinking of getting a predator, and these comparisons seem to favour it well!

edit: clarification
Jun 26, 2008 at 2:00 PM Post #10 of 83

Originally Posted by athenaesword /img/forum/go_quote.gif
that's a great offer mike! too bad i'm too far away to lend you my trips heh. (which i'm secretly thankful for since i'm still at the "gotta listen to em everyday " part). I do hope you'll update if you have the opportunity to test them though. i was thinking of getting a predator, and these comparisons seem to favour it well!

OOPS I goofed. Meant to address that toHeadphone Addict--like I'd let him borrow the IEMs.

Sorry for the confusion
Jun 26, 2008 at 2:08 PM Post #11 of 83

Originally Posted by tnmike1 /img/forum/go_quote.gif
OOPS I goofed. Meant to address that toHeadphone Addict--like I'd let him borrow the IEMs.

Sorry for the confusion

nono i got it. lol. everything after the first line sentence was addressed to HA too. if anything, it was me who caused the confusion lol. editted to clarify.
Jun 26, 2008 at 4:22 PM Post #14 of 83
This is particularly interesting to me, as I'm deciding between Livewires & FreQ Shows, and despite the FreQ shows having three drivers with crossover, you rate the Livewires as being higher quality... any explanation?

Really nice job, HA!
Thanks for all your work!

Jun 26, 2008 at 4:23 PM Post #15 of 83
people tend to think iems doesn't need amplification so synergy between iems and amps seems to be very underrated, even here at head-fi.

good job and thanks HA

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