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DAC/Amp Recommendation

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#1
Hello,

I have a question that I cannot seem to find an answer to while searching various forums and posts.

Current equipment: Sennheiser HD 650 and 598, Objective amp, iphone 7, ipad Pro.

What I would like to do: have a DAC/AMP that I can use to listen to my 650s while sitting in a lounge chair drinking wine/whiskey, etc.

Requirements: Able to use iphone 7 and/or ipad pro as source. I will not be able to use my desktop computer or laptop as a source. An alternative (if there is a good reason) is to purchase a separate portable source device (i.e. fiio, etc.)

I was looking previously looking at the Schiit Bifrost multibit and Asgard 2 amp until I saw the review here indicating the DAC is not very good. I then started looking at the Topping DX7s as a solution.

What would be a good recommendation to meet my needs?
1) iphone -> DX7s -> HD 650
2) ?

Thank you!
 

amirm

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#2
Welcome to the forum Peter. DX7s sounds great with my Sennheiser HD650s. The other is the Pro-ject Pre S2 which I recently reviewed.

I just purchased the iFi Nano iDSD Black which I will be comparing to Chord Mojo that is coming on loan. If you are not in a hurry, you may want to wait for those reviews.
 
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#3
Welcome to the forum Peter. DX7s sounds great with my Sennheiser HD650s. The other is the Pro-ject Pre S2 which I recently reviewed.

I just purchased the iFi Nano iDSD Black which I will be comparing to Chord Mojo that is coming on loan. If you are not in a hurry, you may want to wait for those reviews.
Thank you for the comment. Is this possible: iphone -> DX7s -> Sennheiser HD650? Or, would you recommend a different portable source? Like I mentioned, I could use my iphone 7 or ipad pro which would be preferred for convenience. I do have a laptop, but I would prefer to not HAVE to use it but would if I could not use the previous devices. Using a desktop computer is not an option.

Also, although I have the objective amp, I willing to purchased a DAC/AMP combo that would be superior in performance.

I will wait for your upcoming review!
 

garbulky

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#5
I am not an iPhone user so don't know if it supports external DACs. Hopefully someone who is familiar with Apple products will chime in with the answer. :)
I think it can with the camera connection kit. However theres some limitations on power requirements
 
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#6
I think it can with the camera connection kit. However theres some limitations on power requirements
If the usb receiver in the dac is powered independently, there should be no issue. If the usb receiver/dac depends on power from the source (ipad/iphone), a externally powered usb hub might be needed depending on the power draw from the DAC.

I believe the DX7s is listed as compatible with iOS so it should work. Not sure if a externally powered usb hub is needed. A quick e-mail to topping might be a good idea.
 

LarsS

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#7
If the usb receiver in the dac is powered independently, there should be no issue. If the usb receiver/dac depends on power from the source (ipad/iphone), a externally powered usb hub might be needed depending on the power draw from the DAC.

I believe the DX7s is listed as compatible with iOS so it should work. Not sure if a externally powered usb hub is needed. A quick e-mail to topping might be a good idea.
I've got one of these from SBooster.com as a way to quickly determine if USB power from source is needed

upload_2018-3-5_16-14-6.png
 
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#10
If the usb receiver in the dac is powered independently, there should be no issue. If the usb receiver/dac depends on power from the source (ipad/iphone), a externally powered usb hub might be needed depending on the power draw from the DAC.

I believe the DX7s is listed as compatible with iOS so it should work. Not sure if a externally powered usb hub is needed. A quick e-mail to topping might be a good idea.
Great recommendation. I actually did that last week and finally got a response:

Dear Peter


Thank you for contacting TOPPING support. We are happy to assist.


If you iphone is lightning port, you can connect iphone to DX7s by a lightning to USB camera adapter, and select USB input of DX7s.


Best Regards!
 

LarsS

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#11
Any USB power meter should show whether power is being drawn from USB bus or not.

Fortunately the DX7s has its own power supply so doesn't draw power from USB bus.
Two of my DAC's also has its own power supply, none of them work through USB if I insert the SBooster VBus, so having its own power supply is no guarantee ...
 
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#12
Any USB power meter should show whether power is being drawn from USB bus or not.

Fortunately the DX7s has its own power supply so doesn't draw power from USB bus.
What about the amp section of the DX7s? I have read mixed reviews about it. I also keep reading about the output impedance... what does that mean?

Thank you!
 
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#13
Peter,

Although I can't speak to the quality of the DX7s amplifier (perhaps Amir or one of the other audio engineering members will discuss that in a later post), I can shed a little light on the output impedance. The rule of thumb is that you want your headphone to have at least 8X (8:1 ratio) the impedance of the amplifier's Output Impedance (some even say 10X -- 10:1). In the case of the Topping DX7s the Output Impedance is about 10 ohms. Therefore, for the best fidelity you want to use a headphone that has an impedance of 80 ohms or greater. In the case of your HD650 you are in luck given that it has an impedance (a resistance to current) of 300 ohms. However, if you have a sensitive IEM or headphone (which commonly have impedances of 16-50 ohms) then you will have issues.

This is an insightful article on headphone impedance from NwAvGuy written some time ago, but just as relevant today: http://nwavguy.blogspot.com/2011/02/headphone-impedance-explained.html.
 
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#15
What he said above. :)

Great :)

Now that I keep thinking about what I want... Is it possible to have a unit do the following:
2 channel amp
bluetooth or wireless streaming
DAC
Headphone amp

I am thinking I could have the unit wired to two bookshelf speakers I built for entertaining while also being able to be a really good quality DAC/headphone amp for my HD650s. The Teac Al-503 caught my eye. However I am not sure how good the DAC/headphone amp would be.
 
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#16
Great :)

Now that I keep thinking about what I want... Is it possible to have a unit do the following:
2 channel amp
bluetooth or wireless streaming
DAC
Headphone amp

I am thinking I could have the unit wired to two bookshelf speakers I built for entertaining while also being able to be a really good quality DAC/headphone amp for my HD650s. The Teac Al-503 caught my eye. However I am not sure how good the DAC/headphone amp would be.
Perhaps Sony HAP-S1 or Teac Al 503?
 

dc655321

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#17
@Peter - this offering from Topping may do the trick. Even comes with a Lightning to micro-USB cable (rare!).
Power looks sufficient for hd650 (subject to preferences I suppose).

I just ordered the newer sibling with the es9038q2m.
I think there are some typos (or confusion) in the power specs reported in the above link, but hey, this device ticks all my boxes :)
 
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#18
Teac has some products. Have you considered either the 5th or 6th version of the Aune X1s? They both have an rca line in, and various other inputs.
 
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