Audiophile options for a HQ external USB DAC

If you're interested in something with advanced design, this Topping A-90 discrete sits at the opposite end of the spectrum to the simple quad op-amp design of the little canford amp I've got here. This is just to give an idea of how sophisticated headphone amps can get. You will pay a lot for it of course :). I have to say, this does look like a very nice amp.

www.audiosciencereview.com

Topping A90 Discrete (A90D) - Teardown and personal thoughts

I found not many teardowns with this model, especially with the output transistors uncovered and with surrounding close-ups, so I decided to purchase one for myself (second hand) to pair it with my D90 MQA then write an article here on ASR. Looks like taking the PCB out from the case if somehow...
www.audiosciencereview.com www.audiosciencereview.com
 
blackbird9 said:
If you're interested in something with advanced design, this Topping A-90 discrete sits at the opposite end of the spectrum from the simple quad op-amp design of the little canford amp I've got here. This is just to give an idea of how sophisticated headphone amps can get. You will pay a lot for it of course :). I have to say, this does look like a very nice amp.

www.audiosciencereview.com

Topping A90 Discrete (A90D) - Teardown and personal thoughts

I found not many teardowns with this model, especially with the output transistors uncovered and with surrounding close-ups, so I decided to purchase one for myself (second hand) to pair it with my D90 MQA then write an article here on ASR. Looks like taking the PCB out from the case if somehow...
www.audiosciencereview.com www.audiosciencereview.com
Click to expand...

That's a nice unit (and teardown).
 
Yes, ASR has some quality content.

I think that Topping amp would be somewhere near the current state of the art, looking at the measured performance he got, the build quality and the features they added. The op-amp version of the A90 gives the same measurements, but they added some nice upscale features to the 'D' version (covered in the 'pros and cons') section and the review conclusions. The only thing I don't like is the main-pcb mounted headphone jack sockets, I prefer headphone sockets to be mounted on daughter boards so that the sockets can be easily replaced when they inevitably break from having the jack plugs pushed in and out repeatedly; but for a home unit this is probably less important.

For anyone interested in making their own, Doug Self's website is of course one of the best resources in the world: http://douglas-self.com/
- though I wish he would update it to https!

And his book "Small signal audio design" is really the business (available on amazon, etc)

Small Signal Audio Design: 4th edition

The Douglas Self Site, audio amplifiers, Small Signal Audio Design
douglas-self.com

Another good book (that unlike the Self book is free!) is the natsemi audio book from 1977, admittedly this is now out of date, but it covers a lot of good ground.

archive.org

National Semiconductor Audio Handbook 1977 : National Semiconductor Corporation : Free Download, Borrow, and Streaming : Internet Archive

National Semiconductor - Audio Handbook 1977
archive.org
 
Just a bog-standard 3.5mm stereo cable... don't need anything special. On the one I've got the input is stereo 3.5mm jack, so I use one like this.

www.ebay.com

AUX Headphone 3.5mm Cable Male to Male Car Stereo Audio Cord Headphone PC Car | eBay

Model Number: Baseus M30 Stereo Audio Aux Cable. Style: 3.5mm Stereo Audio Aux Cable. Type: AUX Cables. Connector A: AUX. Connector B: AUX. Type: 3.5mm male-to-male Aux Cable. This cable is a great solution to protect your 3.5mm aux port from repeat pluging and unpluging.
www.ebay.com

Or if your headphone amp has 1/4" jack or 2 phonos, then you need the appropriate cable. Doesn't need to be anything expensive. It might be worth paying a little more for gold plated connectors, but I wouldn't worry about anyting like OFC cable or the other nonsense. The cable I'm using right doesn't even have gold plated plugs.
 
One more tip, if you're connecting the headphone output of the thinkpad into the line input of the headphone amp, then I would keep the master volume on the thinkpad fairly low, say 30%, and turn up the volume on the headphone amp itself, to avoid clipping in the headphone amp input stage. At least try that to start with. Let the headphone amp do it's job rather than feeding it with too high an input signal. You can then experiment with increasing the output of the pc's headphone socket.

Of course if you're connecting the line output of the PC into the headphone amp then this isn't an issue.
 
And if that doesn't improve your sound quality, then I recommend a snifter of Hine cognac, and then settle back and enjoy 😁
324-2511681099.jpg
 
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