[RickB]

  I bought the iPhone 6S in switching over from a Blackberry.    I use Shure 535s with an iPad Air.    I would like to use it with the iPhone 6S, but because I need the ugly external battery, I can not use the 535s or even my Etymotics without some kind of adapter or without removing the battery.     Is anybody aware of a straight through adapter which will work with the Apple Smart Battery and enable my earphone usage?

Would this work?
 
http://www.amazon.com/MobilePal-Extender-Connectors-Lifetime-Warranty/dp/B00KE5NJ7W/ref=sr_1_1?ie=UTF8&qid=1451128019&sr=8-1&keywords=iphone+headphone+jack+extender
 
If you do a search for iphone headphone jack extender on Amazon, several examples come up.

 

[sclemmons]

Big help.  Order in.  Thanks.  sc

 

[ubs28]

Try the iPhone cable from Shure since the original cable of the Shure SE535 is not compatible with most cases for the iPhone or iPad. It also comes with a remote control. Shure is aware of this problem with the Shure SE535 since this issue is fixed with the Shure SE846 cable. 

 

[LocutusEstBorg]

  You can disagree all you want; until you test it yourself, you are just speculating.  If you own super low impedance iems like the SE846, EQ8 and Angie, you can hear the difference in 1 or 2 ohm on sources.  Super low impedance iems being anything that dips below 10 ohm in their impedance graph.  All 3 I mentioned do and I have first hand experience hearing the differences and of course the differences occur in frequency response at the point of the low dip in impedance.  It's just the way multi-ba's, crossovers and impedance work. 

 
 
Edit: It made the SE846 boomy when using an iPhone 5 (around 4.5 ohms) versus a v200 or cypherlabs duet at the time (both less than 1 ohm). The EQ8 gains treble presence and losses bass. The iPhone 5S (2.3 ohm) had slightly less bass and slightly more treble than the cypherlabs picollo, and the AK240 had a fair amount less bass and a good bit brighter with the same E-Q8 (which is a single BA). Angie would get darker in treble with more impedance.  The iPhone 5S was slightly more rolled off than the picollo. The change in enjoyment with all of them was significant between sources. 

Is it possible for you to do a comparison between an iPhone 6/6S and any < 1 ohm headphone amp (known to have a flat response so it can be compared with the iPhone) and the SE846?

 

[shotgunshane]

 
Is it possible for you to do a comparison between an iPhone 6/6S and any < 1 ohm headphone amp (known to have a flat response so it can be compared with the iPhone) and the SE846?

Unfortunately I don't have access to the SE846 any longer. The set I had was a 2 week loaner from a friend. 
 
Since then I had an opportunity to briefly hear an SE846 with modded filters. I don't remember the details of the mod but I thought it sounded significantly better than stock on an iPhone 5S at the time. It had much greater treble energy and sparkle. Moedawg140 was the owner of that pair and I believe he owns an iPhone 6 or 6s if I'm not mistaken. He might be a good one to answer your question.  He as the QP1R dap too. 

 

[ubs28]

 
Is it possible for you to do a comparison between an iPhone 6/6S and any < 1 ohm headphone amp (known to have a flat response so it can be compared with the iPhone) and the SE846?

The Shure SE846 is more neutral and the bass is tighter and deeper. 

 

[LocutusEstBorg]

 
The Shure SE846 is more neutral and the bass is tighter and deeper. 

Is the difference worth the nuisance of carrying a separate headphone amp and worrying about a second battery to recharge? I'm mainly going to be using this in the gym or the car where there may be outside low frequency noise like the engine.
 
If the SE846's sound quality with the < 1 ohm headphone amp is 10/10, how much would you rate it on the iPhone 6?

 

[LocutusEstBorg]

This graph should give an idea of the iPhone 6 vs 1 ohm amp for low impedance IEMs. It looks like the maximum deviation across the frequency response between 2.2 ohm and 1 ohm output impedance is just 1 dB.

 

[vnmslsrbms]

 
Is the difference worth the nuisance of carrying a separate headphone amp and worrying about a second battery to recharge? I'm mainly going to be using this in the gym or the car where there may be outside low frequency noise like the engine.
 
If the SE846's sound quality with the < 1 ohm headphone amp is 10/10, how much would you rate it on the iPhone 6?

I don't think the difference is huge especially for BA phones like the SE846.  It's really worth it with IE800s, but instead I've just chosen to relegate those to my work setup.  It's one way I justify having more than 1 IEM.  When I'm moving around, convenience is king.  Carrying a stack means you have to mess with cables, charging multiple devices, 

 

[shotgunshane]

The IE800, like 99.9% of single dynamic driver based in-ears, has a flat impedance curve. Output impedance is not going to have any effect on its frequency response. Zero. If you want to talk about the sound the amp has, that is completely different than the science of output impedance and its affect on drivers.

Almost all BA based in-ears will deviate to some degree their target frequency response by adding impedance. The varrying degree is shown in their impedance curves. Some are minimal and some are quite wild and large. How do you think Etymotic reaches their target diffuse field frequent response? By simply adding impedance. The ER-4PT model has around 23 ohms impedance but the ER-4S, using the same single balanced armature, has 100 ohms impedance.

 

[elfary]

 
Is the difference worth the nuisance of carrying a separate headphone amp and worrying about a second battery to recharge? I'm mainly going to be using this in the gym or the car where there may be outside low frequency noise like the engine.
 
If the SE846's sound quality with the < 1 ohm headphone amp is 10/10, how much would you rate it on the iPhone 6?

 
I'd rate it as 95% at least. I don't even bother to use my iBasso T3 amp (0'3 ohms output impedance) at the office. Let alone on the go.
 
iPhone 6 + Shure SE846 sound is amazing on its own right. Tight, powerful and clean. As portable as it gets giving away almost nothing. I would not bother with anything else really.

 

[ubs28]

 
Is the difference worth the nuisance of carrying a separate headphone amp and worrying about a second battery to recharge? I'm mainly going to be using this in the gym or the car where there may be outside low frequency noise like the engine.
 
If the SE846's sound quality with the < 1 ohm headphone amp is 10/10, how much would you rate it on the iPhone 6?

 
For the gym, just use the iPhone. I don't even use my Shure SE846 in the gym, that's what my older Shure SE535 and Shure SE215 are for to give an indication how much I care about sound quality when I work out. 
 
For car use, it is highly dependent on how much noise the car makes. So it's really something that I cannot answer since I don't know how loud your car is.
 
It's hard to put a number on it, but I don't rate the iPhone very highly for IEM's like the Shure SE846 in comparison to 0 ohm output devices. It's not sounding like it should sound.

 

[themelz]

  I've been using my Beyerdynamic A200p dac/amp with the iPhone 6S+ this week, to test some multi-armatures and wanted the A200p's 1.1 OI.  It randomly looses connection with the iPhone and blasts me with white noise very loudly.  This never happened before iOS9 and when I had the 5S.  Unfortunately Beyerdynamic chooses to ignore my emails.

I just got a A200p to use with my iPhone 6s and have the same white noise problem. Have you been able to resolve that?

 

[shotgunshane]

I just got a A200p to use with my iPhone 6s and have the same white noise problem. Have you been able to resolve that?

I haven't used it since I made that post. I need to check and see if recent iOS updates make a difference.

 

[themelz]

I haven't used it since I made that post. I need to check and see if recent iOS updates make a difference.

It shouldn't. My iPhone 6s was brand new and I had already updated to the latest iOS. Sounds like you never heard back from Beyerdynamic.