Topping A90 Discrete - Official Thread

I didn’t find a topic for this product, so I figured I’d start one because I would love to read impressions and thoughts from this community.

Topping recently released a discrete design of their A90 headphone amplifier, for which they use 156 (4x39) matched transistors instead of opamps for its gain and output stages.

Product Information

My Initial Thoughts

Aside from the engineering flex of producing a measurably performant discrete topology, which I applaud, I remain unsure if or how that translates to any experiential improvement to similarly performing IC designs.

Instead, what I find most compelling about this amplifier is that it can produce 6W per channel at a 32 ohm load, and it has a resistor ladder volume control implementation for perfect channel matching and longevity (scratchy volume pots anyone?). The latter is something I personally highly value and is one of the potentially more audibly important vectors that amplifier designs have been under-indexing on while they needless chase different degrees of completely inaudible SINAD performance.

Measurements

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I don’t like the removal of physical switches, and I really wish they had a 3.5mm output instead of that 4.5mm one for IEMs. The remote, while seems functional, doesn’t really look intuitive at all.

All that said, I have been looking to replace my Jot 2 with something that allows me to turn off headphone out and use my IEMS as well as my headphones - so I am very interested in seeing some user reviews.

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Agreed. The haptics of physical switches can’t be beat.

That said, according to its manual, one can still switch inputs by clicking the volume knob (and output by “double-clicking” the volume knob), but I think you can only adjust gain by remote control.

The 4.4mm is not really just for IEMs, I would say that the majority of people who are going balanced with headphones opt for the 4.4 over an XLR4 lately.

A 6.35mm (1/4") to 3.5mm adapter is something that is very easy to find and is available with a low profile, whereas an XLR4 to 4.4mm, or 4.4mm to XLR4, is not so easy (or cheap) and is usually on the large size.

Just my tuppence.

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Has anyone spent time talking about how well implemented the volume control / preamping is?

Cheap for a relay based pre…

The amp comes with a 6.35mm to 3.5mm adapter according to the Headphones.com product page:

As for my impressions of the amp, I’ve never owned any of Topping’s products so I am unfamiliar with their sound or build quality from a first-hand experience. The previous version seemed popular enough though.

As others said in their replies, the reduced gain stages along with volume control is interesting. Topping also has an add-on that can increase the number of XLR and RCA inputs, though I’m not what use case that product is supposed to address. Because of the removal of physical switches and the reliance on a remote control, I am inclined to believe that this product is targeted more towards somebody that would have this as part of a home audio system in a living room or den as opposed to a desktop setup.

Regards,
Vic

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I suppose if someone wants to try different DACs with the same amp this could be useful.

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That was the first thing that came to mind and could potentially be a helpful feature for somebody A/B-ing DACs.

The Ext90 adds 3 additional pairs of XLR and 1 additional pair of RCA inputs to the built-in 1 pair of XLR and 1 pair of RCA connectors. I could see the Ext90 being useful if the use case required more than 1 set of balanced or unbalanced sources, such as an external CD transport, Blu-ray/DVD player, and a standalone music streaming source. This again suggests that a target audience is the home audio system owner.

As an aside, I wonder how much Topping has learned from their Pre90 and applied to the A90 Discrete?

Regards,
Vic

Are the pre outs mute-able? Or auto mute with headphones plugged in?

You can cycle between preamp out, headphone out, and preamp+headphone out. You have two memory buttons on the remote control, so you can save one for pre-out only and one for headphone out only.

Ditto. Been meaning to replace some volume pots in older gear with something like this.

Lou

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Looks like Topping released a firmware update that allows users to change the gain setting without using the remote. It also adds a handful of different volume curves for the volume control.

https://www.tpdz.net/newsinfo/663543.html

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They actually pulled the firmware update v2.0 at the last minute, due to bugs. They just recently released the updated firmware v2.3, which I confirmed works! It also seems to have resolved my issue of resetting when plugging/unplugging to the 6.35mm unbalanced port, instead showing a -5.

https://www.topping.audio/newsinfo/663543.html

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Thanks for your review! May I ask what DAC you are using with your A90D?

Thanks for the info! I also have an AKM chip DAC called the SMSL D-6, and like it over the ESS Sabre-based Topping D10 Balanced as well when paired with the A90 Discrete :slight_smile:

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Has any one here used A90D with Topping D90SE (the stack), and how did that work for you?

I have my A90D paired with the Denafrips Ares II. Absolutely spectacular. Cannot recommend enough. I have not been in this world as long as others, so maybe others have heard something better than this pairing, but I have not. They go great together. (2021 LCDX is the headphone that seems to best sing together, but this stack would work with any headphone, and has a ton of power)

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Pls can you say more? How did you find bass, mids, treble? Imaging and soundstage?

Sure thing - though I’ll preface that many here are a lot longer/more experienced than me so take with a grain of salt. I found everything extremely detailed. Imaging really nice. Musicians sitting next to me in the room type of detailed, hearing singers take a breath, fingers moving on guitar strings that I never noticed before. That was the biggest thing. The other major item that jumped out at me was bass. Really detailed, 3-dimensional bass that let me see things that were new. I boosted a hair, but it’s really good without. On vocals, I’d say this setup was comparable to the WA 3rd Gen fireflies on something like Vincent (Ellie Goulding) where there are isolated female vocals. Not quite as intimate as the tubes, but really not far off. Strong enough that I unplugged the fireflies and put them in the closet. Soundstage not huge, but good and I could really separate and “see” the instruments around me. I’ve not listed to amps noted for a huge soundstage, so I could be limited in my experience, but better than WA7 and DX7 Pro and Cobalt Blue. But the main thing that struck me is that everything is at a high level, with really no weaknesses I could find.

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Thanks - excellent. Great review. Seems a good addition to your system. I’ve been considering the Pontus 2 given that I will probably upgrade my amp in the future - my alternative is the Matrix Element series since I’m a Roon streamer but overall this is the stronger leaning.

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