Qudelix T71 Portable DSP DAC & HP Amp

[Merkurio]

The power of a highly positive review at ASR ?

I have no idea how many were 'in stock', but...

The Qudelix T71 DAC/Headphone amplifier is now 'currently unavailable' at Amazon USA after being in stock for all but a handful of the past 393 days - per a price history at Keepa dot com.

Keepa.com - Amazon Price Tracker

Amazon price history charts, price drop alerts, price watches, daily drops and browser extensions.

keepa.com

EDIT - perhaps this will incentivize 'Drop' to pursue offering the Qudelix T71 dongle at a discounted price.

Unfortunately, for this kind of audio product in such a small niche of the market, if you’re not a well-known name or you don’t stand out thanks to a lot of marketing mumbo jumbo, you’re pretty much guaranteed to stay in the shadows, no matter how many boxes you tick compared to the other options out there.

The 5K is relatively popular and the T71 has been on the market for more than two years now, with a somewhat active thread I started on Head-Fi. Still, in the end, very few users actually know about it (it’s basically a conversation among the handful of us who own one). That’s why I was really happy to see Amir’s review, and I hope it helps the product gain some traction.

 

[jasonhanjk]

I don’t think this the correct way to look at it: these measurements are about max. power, they are not trying to assess noise. If you were to operate at 1mW and wanted minimum noise, you would go in low-gain and/or use the device built-in volume control when available. See earlier @jkim post and his link to the 5K measurements that explain this better.

If you’re concerned about noise, I believe the 50mV measurement is a better metric: the T71 is ~88dB, whereas the Tempotec Sonata BHD Pro you referenced is ~93dB. The BHD Pro is quieter, but I’m not sure the difference is that meaningful. I would trust Amir’s comment: “not the quietest amp but still, above average.” I believe that’s the price you pay for having 8V available on the output.
So, if you only use low-impedance IEMs, are concerned about noise, and want the lowest price, then yes, the BHD Pro may be a better choice… although I’m not sure it has this built-in analog volume control feature.

Both 50mV data and THD+N graph can be use, the THD graph is much faster to look at to decide how much noise is acceptable to me.

The way I grade DAC is:

1. Priced below $100
2. Capable to drive IEM 16 ohm or less, without increase in distortion
3. Very low noise, meaning balance output is out due to increasing 3dB noise (theoretical value)
4. Crosstalk < -72dB
5. Bonus. Variable analog output. This feature will lower the noise even further.

 

[jasonhanjk]

As @CedarX pointed out above, for low-level noise performance, you want to see the 50 mV SNR measurement. Here's a reason.

And you know what? The reason why the TempoTec Sonata BHD excels in the above chart is simply because of the CS43131 DAC chip's built-in Dynamic Range Enhancement (DRE). Its net effect on noise performance is no different than engaging manual analog volume control. However, it is not an ideal way to use analog attenuation, as shown in my review here and here. Its byproduct, DRE-induced distortion, is not acceptable in my view. With DRE turned off, all CS43131-based devices' SNR @ 50 mV becomes worse than the Qudelix T71's. For this reason, it is a proper view that whenever analog attenuation is available, it should be offered in the form of manual volume control (i.e., gain adjustment), NOT in the form of automated DRE.

The T71 have the ESS IMD hump.
Both of the mention DAC have their own weakness.

 

[jkim]

The THD graph is much faster to look at to decide how much noise is acceptable to me.

Again, the THD+N graph does not make a fair comparison due to some devices adopting DRE (i.e., signal-dependent analog attenuation).

The T71 have the ESS IMD hump.
Both of the mention DAC have their own weakness.

DRE-induced distortion is not comparable to the ESS IMD hump. I have not seen any reliable listening test that renders the ESS hump consistently audible---and it's measurably much lower, too. DRE distortion is a clear engineering mistake that is audible in a test.

 

[Power Pop 23]

Impressive performance! Any plans to test the dedicated IEMs from Qudelix? According to the manufacturers site they can only be used with the T71:

T71 IEM

Qudelix Bluetooth Qualcomm QCC512x ES9218P ESS DAC USB SONY LDAC Headphone Amp HiFi Audio aptX

www.qudelix.com

Yes,

Amir has confirmed he will measure the T71 IEM.

I do not know when the review will be posted.

 

[Egoquaero]

Hi dears,
am I the only one who finds static noises/interference noises unbearable on the T71 when on cellular data?
This happens especially when I change tracks.
I use an iPhone 16 pro max along with the qudelix t71 magnetic case; 4.4mm Balanced output; Xenns Top Pro iem.
I came from using a Topping G5 which doesn't have any of these noises.
Someone on head-fi forums told me that it has to do with the cellular data signal or something where I from (Italy). Does it make sense to you?
Is there anything I can do to make it better? My way to cope with this so far is to download an album and then listen to it on airplane mode. It’s obviously annoying.
Do product reviews measure this by any chance? Because I think a product can appear perfectly perfect on so many levels (dac distortion, dynamic range, noise floor, etc.) but then an issue like this makes it unusable under certain conditions. And in my case I mostly use it while streaming with 4g 5g cellular data. Oh and in no way, I'm saying this to criticise anyone's work, but just for the sake of conversation and knowledge.

 

[staticV3]

Someone on head-fi forums told me that it has to do with the cellular data signal or something where I from (Italy). Does it make sense to you?

Yes. The worse the signal strength, the higher your phone's transmission power, the worse the interference noises will be.

Is there anything I can do to make it better?

Disable 5g/4g, which will improve signal strength and reduce transmission power.

Do product reviews measure this by any chance?

No chance. Repeatable RF tests/measurements are highly specialized and not something an audio reviewer would usually be capable of.

 

[jkim]

Hi dears,
am I the only one who finds static noises/interference noises unbearable on the T71 when on cellular data?
This happens especially when I change tracks.
I use an iPhone 16 pro max along with the qudelix t71 magnetic case; 4.4mm Balanced output; Xenns Top Pro iem.
I came from using a Topping G5 which doesn't have any of these noises.
Someone on head-fi forums told me that it has to do with the cellular data signal or something where I from (Italy). Does it make sense to you?
Is there anything I can do to make it better? My way to cope with this so far is to download an album and then listen to it on airplane mode. It’s obviously annoying.
Do product reviews measure this by any chance? Because I think a product can appear perfectly perfect on so many levels (dac distortion, dynamic range, noise floor, etc.) but then an issue like this makes it unusable under certain conditions. And in my case I mostly use it while streaming with 4g 5g cellular data. Oh and in no way, I'm saying this to criticise anyone's work, but just for the sake of conversation and knowledge.

@staticV3 covered your main questions above.

This noise phenomenon, called RFI demodulation, depends on both the phone side and the DAC device side. For instance, you may not experience the same level of noise if you connect the T71 to another phone. One thing clear, based on what you reported, is that in designing the T71, the engineer most likely did not fully address potential RFI demodulation. RF noise can creep into the signal from both the power supply and signal path. Filters are needed at multiple levels: USB power input, USB data line, supply rails, and each op-amp stage. The 71 designer must have neglected some of these filters.

 

[Egoquaero]

Thank you so much. Why didn't I have the same problem with the Topping G5? Better some sort of shielding?
I still prefer the qudelix t71, the eq capabilities, power delivery, small size, low distortion... There's nothing even close in the market
EDIT: @jkim you replied when I was writing this message, you might have answered my question

 

[Merkurio]

Thank you so much. Why didn't I have the same problem with the Topping G5? Better some sort of shielding?
I still prefer the qudelix t71, the eq capabilities, power delivery, small size, low distortion... There's nothing even close in the market
EDIT: @jkim you replied when I was writing this message, you might have answered my question

If you haven’t already, I’d recommend sharing your issue on the official Qudelix forum with all the details, so they can take it into account for future revisions or new products.

It’s definitely something worth considering, and they may also be able to offer additional support (or even a replacement).

 

[Mattyesfan]

The power of a highly positive review at ASR ?

I have no idea how many were 'in stock', but...

The Qudelix T71 DAC/Headphone amplifier is now 'currently unavailable' at Amazon USA after being in stock for all but a handful of the past 393 days - per a price history at Keepa dot com.

Keepa.com - Amazon Price Tracker

Amazon price history charts, price drop alerts, price watches, daily drops and browser extensions.

keepa.com

EDIT - perhaps this will incentivize 'Drop' to pursue offering the Qudelix T71 dongle at a discounted price.

I saw they were out of stock on Amazon but finally decided to purchase the T71 through their website. I ordered on the evening of January 20th and it arrived today, the 23rd (I’m in Kentucky). Free FedEx shipping. From Korea. It beat 4 packages I’ve been waiting a week or more to receive through USPS from the continental US.

Glad I finally pulled the trigger on this, because it is truly an amazing device! The PEQ setup was so simple and having those settings stored and able to use on the go with my iPhone is awesome. With the incoming winter storm I should have plenty of time to mess around with it this coming week, but after only a few hours I’m incredibly impressed.

 

[gabege]

Your interpretation is correct. You will be able to listen reasonably loud but if you push it, it will clip and distort badly. Alas, I can't say what is loud to you vs me. So the ultimate answer is hard to get.

Would you have more power with headphones like the Noire X if you ran them balanced?

 

[Power Pop 23]

FYI,

The Qudelix T71 'dongle' is again available to order at Amazon USA.

 

[Atanasi]

Do you know if the USB configuration protocol is the same as 5K? That is, does this work with devicePEQ tool that supports 5K?

 

[Sebby]

Thank you so much. Why didn't I have the same problem with the Topping G5? Better some sort of shielding?
I still prefer the qudelix t71, the eq capabilities, power delivery, small size, low distortion... There's nothing even close in the market
EDIT: @jkim you replied when I was writing this message, you might have answered my question

I have that issue instead with the Topping G5. I used to strap it with rubber bands to an old Sony Xperia Compact that I use as a DAP.
When Wi-Fi was enabled, every time streaming content loaded, very annoying noises would appear

 

[lateparty]

I have had my DCA E3 almost exclusively plugged into my T71 since I got the device in July 2025 and never had any issues with distortion and use PEQ with a solid bass shelf. It’s a shame that the low impedance and this device causes an issue with the Noire X. In Amir’s own review of the Noire X

Quickly switching from E3 to NOIRE X resulted in noticeably higher volume. This will open up a lot more headphone amplifiers that can drive the NOIRE X.

But I noticed earlier in the thread here he said the Noire X would have lots of distortion if played loud, and we al have different definitions of loud.

 

[gabege]

I have had my DCA E3 almost exclusively plugged into my T71 since I got the device in July 2025 and never had any issues with distortion and use PEQ with a solid bass shelf. It’s a shame that the low impedance and this device causes an issue with the Noire X. In Amir’s own review of the Noire X



But I noticed earlier in the thread here he said the Noire X would have lots of distortion if played loud, and we al have different definitions of loud.

I just got the T71 and am driving the Noire X balanced with no problems yet. I can play them pretty loud...louder than I'd ever want so I think it's ok. From a technical point of view I'd love to know if there's more headroom because of driving them balanced.