They have at least QA/QC issues. Half of my Topping devices work roughly as advertised, half totally don’t. For example I have two E30, black and silver. One of these works fine, the other one outputs really noisy and distorted signal. The D90SE I have is also horribly bad. D30Pro I have works just like it should.
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Can be found on Shenzhenaudio’s site.
S.M.S.L D300 USB Firmware [221012]
S.M.S.L D300 MCU Firmware [221012]
Both from Feb 20,2023
I couldn’t get the usb update to launch. Missing DLL error is all I get. No other info.
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Question, how does this work with HQP? I mean DSD has to be sampled to PCM to do the EQ stuff right? Are you saying that HQP would upsample to DSD again and send to the DAC?
If so, what PCM resolution does HQP sample to for say DSD256? If it’s less than PCM 768kHz then it’s downsampling and losing information.
(How did I come up with the 768 number? DSD256 = 11.2Mhz on one bit; on 16 bits: 11.2M/16 = 700kHz. With 24 bits is 467KHz.)
Yep this will do me nicely for my home office until I get a Holo Spring 3
Or maybe they’ll incorporate a “Red” ethernet input in their Spring 4?
This is the TRS to XLR cable I got (popular amongst the Pro audio crowd). Very good and approx $20 for a pair:
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To use your example, then your 1bit 11.2 MHz track will be converted to 64-bit (or could be 80-bit with HQPlayer?) 11.2 MHz for any DSP operations , before modulation to 1-bit 11.2 MHz output
Sample rate unchanged
So no worries. Just sit back and enjoy the tunes 
It is processed as SDM. If you start with DSD256 and output is DSD256, it stays 11.2 MHz all the time without any rate conversions.
For example if you start with DSD64 and output is DSD512, then 2.8 MHz is converted directly to 22.5 MHz without any intermediate rates.
What ever DSP you choose to do here, EQ, convolution, whatsoever doesn’t affect this.
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If you use mac or Ubuntu Desktop, you can probably update it using virtualbox
And an un-activated Win 10 ISO image install, which you can download free from Microsoft
I don’t think un-activated would prevent this
Free to try
I’m interested in the SMSL D-6, but my amp is single-ended only. Sounds like most folks here are using the D-6’s balanced TRS output. Does anyone know if its single ended output measures just as well as balanced for DSD256/512 (or at least well enough to not be problematic)?
I do my wide band measurements usually from single ended outputs, because the tools are single ended (coaxial input).
Based on those, it looks fine to me. Only slight issue is noise from the built-in switching PSU that spans from 100 kHz to 300 kHz. But it is relatively low level (below -80 dB). Audio band should be pretty clean though.
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I can only measure up to ~80 kHz accurately with my Cosmos ADC but D-6 is very clean with RCA outputs
Note I measured with Intona galvanic isolation of the USB input, which can help nicely, depending on USB source.
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Thanks Jussi and dabassgoesboomboom, I will give the D-6 a go.
Regarding galvanic isolation, I use a Raspberry Pi 4 running NAA as USB source. Do you think an Intona isolator would provide a noticeable improvement for my setup?
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a great simple test you can do is to power your RPi4 with a 5Vdc USB powerbank - this will make your USB source isolated from any AC mains currents and the Pi’s PSU leakage currents.
Just make sure powerbank can output 2A, to make sure the RPi4 can be powered properly.
This battery test eliminates all AC power related noise / currents , which mix with RCA signal output.
If you don’t hear any difference with battery vs PSU, nothing much to worry about
Unless you still want objectively better performance (without needing to charge a powerbank all the time) , then you can look at a USB isolator
It will almost definitely improvement measurements , especially with RCA output
Archimago just reviewed Intona and showed huge measured difference with RCA output DAC:
Archimago's Musings: MEASUREMENTS: Intona 7055-C USB 3.0 SuperSpeed Isolator. And Darko & Lavorgna hear no difference with the Silent Angel ethernet switch. [Importance of open discussions.]
Its very expensive compared to D-6 price,
There is a new Topping USB isolator that is much more affordable. They’ve improved the specs quite a bit over their first model. Link below.
It’s still nearly the price of the DAC , But of course you can use it with future USB DACs
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Archimago also measured the original Topping HS01 USB isolator which is even cheaper than new HS02.
And it made quite similar improvement as Intona.
Intona vs HS01 pics below:
Topping HS01:
Intona 7055-C:
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Wow! Missed that! I’m Intona owner and happy with it!
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If you update your D300, can you let me know if you had issues getting the usb board update to launch. I still get the missing dll error.
Everything went fine according to the instructions for me. Result was a bricked device… 
Oh well…
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Eek 
I got the main board updated. I don’t know what it changed though.
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Hardware update to the board - or firmware ?
Firmware
S.M.S.L D300 MCU Firmware
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That’s the one that bricked mine… I can flash it over and over again to the device. But after writing it, the DAC doesn’t return to life.
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