[MiguelP]

I didn’t say that ‘other Class-A amps do not get hot’. Please don’t misquote me. I know perfectly well what I meant. Also the Chord Mojo 2 does not clip above 3V and it’s SINAD has been measured best between 3v and 4v. https://www.audiosciencereview.com/...hord-mojo-2-review-portable-dac-hp-amp.34160/

There's nothing special about 200mA of current into 32ohms as other manufacturers seem to be able to that in full Class-A with no overheating issues.

Not sure if it uses 200ma or less but if you're worried about overheating maybe you should look elsewhere than the Xduoo TA-22..

And yes I know about that review of the Chord Mojo 2 but I find it sounds better in lower voltages - the blue color which I see now is even lower (1.5V). I find that the sound becomes a bit harsh above 3V and that it starts to clip during louder passages. At maximum voltage it's unusable.

 

[davehutch]

There's nothing special about 200mA of current into 32ohms as other manufacturers seem to be able to that in full Class-A with no overheating issues.

Not sure if it uses 200ma or less but if you're worried about overheating maybe you should look elsewhere than the Xduoo TA-22..

And yes I know about that review of the Chord Mojo 2 but I find it sounds better in lower voltages - the blue color which I see now is even lower (1.5V). I find that the sound becomes a bit harsh above 3V and that it starts to clip during louder passages. At maximum voltage it's unusable.

There is a big difference between 'overheating' and 'getting hot'.
Class-A amps need to get hot as I'm sure you know, it's part of their make-up and a necessity. It's how it's managed. If Aune had put better ventilation holes in and maybe a fan inside, you might be able able to run it in Class-A all the time.
I'm quite happy with an amp that gets hot. It just needs to stay in Class-A and not require a USB fan or a makeshift platform to do so. I'd hate to go through the summer months constantly checking to see if the amp had switched out of Class-A rather than simply enjoying my music.

Regarding your clipping, are you driving headphones directly or using it as a DAC? If you're hearing the clipping on headphones, then something is wrong with your Mojo 2. If you're using it as a DAC, are you sure it isn't your amp's input clipping?
I can't see the input sensitivity mentioned on Aune's website or in the user manual for the S17... @AuneAudio can you clarify please?

 

[MiguelP]

There is a big difference between 'overheating' and 'getting hot'.
Class-A amps need to get hot as I'm sure you know, it's part of their make-up and a necessity. It's how it's managed. If Aune had put better ventilation holes in and maybe a fan inside, you might be able able to run it in Class-A all the time.
I'm quite happy with an amp that gets hot. It just needs to stay in Class-A and not require a USB fan or a makeshift platform to do so. I'd hate to go through the summer months constantly checking to see if the amp had switched out of Class-A rather than simply enjoying my music.

Regarding your clipping, are you driving headphones directly or using it as a DAC? If you're hearing the clipping on headphones, then something is wrong with your Mojo 2. If you're using it as a DAC, are you sure it isn't your amp's input clipping?
I can't see the input sensitivity mentioned on Aune's website or in the user manual for the S17... @AuneAudio can you clarify please?

Chord Mojo 2 clips at its maximum voltage. Mine and everyone's else. I use it both as a DAC and as an headphone amp.

The S17 Pro always works in class A mode.

What's the operating temperature of the Xduoo TA-22? Are you sure it is lower than 69 °C? Also what is it's current? Are you sure it's 200 ma (100 ma per channel)?

 

[davehutch]

Chord Mojo 2 clips at its maximum voltage. Mine and everyone's else. I use it both as a DAC and as an headphone amp.

The S17 Pro always works in class A mode.

What's the operating temperature of the Xduoo TA-22? Are you sure it is lower than 69 °C? Also what is it's current? Are you sure it's 200 ma (100 ma per channel)?

Addressing your three comments in order:

1. That's not what you originally said...you said "I find that the Mojo 2 works better between 2 and 3 V. Above 3V it starts clipping"
Now you are happily quoting that it clips above 4.3V?
I'm pleased to see you've realised you were incorrect.

2. According to this review by Soundnews, the amp uses Class-A/B for the 50mA mode - but if that isn't the case, I stand corrected.
Again, @AuneAudio can you please clarify whether the S17 Pro uses Class-A/B mode for 50mA?

3. I've never said the TA-22 gives you 100mA/ch. Nor do I care about its operating temperature. What I have said is that is in many cases (judging by this forum), the S17 Pro states it does offer 100mA/ch, but clearly cannot do that consistently, without modifications at the owners' expense.
Nowhere does Aune state that you must use a particular type of headphone cable or a cool room otherwise you can't consistently use the 100mA mode.
As a further example, the Violectric and Burson make amps that can use Class-A mode continuously, without overheating and having to adjust their operating mode. They don't need platforms, feet or fans.

I'm glad that you're happy with the amp and your platform and your fan and I'm glad that you think it is worth the effort. That's great.
Personally I would like an amp that uses Class-A consistently, without me having to make modifications.

I do hope that's all clearer now and I look forward to @AuneAudio clarifying the two questions I asked them.

 

[MiguelP]

Addressing your three comments in order:

1. That's not what you originally said...you said "I find that the Mojo 2 works better between 2 and 3 V. Above 3V it starts clipping"
Now you are happily quoting that it clips above 4.3V?
I'm pleased to see you've realised you were incorrect.

2. According to this review by Soundnews, the amp uses Class-A/B for the 50mA mode - but if that isn't the case, I stand corrected.
Again, @AuneAudio can you please clarify whether the S17 Pro uses Class-A/B mode for 50mA?

3. I've never said the TA-22 gives you 100mA/ch. Nor do I care about its operating temperature. What I have said is that is in many cases (judging by this forum), the S17 Pro states it does offer 100mA/ch, but clearly cannot do that consistently, without modifications at the owners' expense.
Nowhere does Aune state that you must use a particular type of headphone cable or a cool room otherwise you can't consistently use the 100mA mode.
As a further example, the Violectric and Burson make amps that can use Class-A mode continuously, without overheating and having to adjust their operating mode. They don't need platforms, feet or fans.

I'm glad that you're happy with the amp and your platform and your fan and I'm glad that you think it is worth the effort. That's great.
Personally I would like an amp that uses Class-A consistently, without me having to make modifications.

I do hope that's all clearer now and I look forward to @AuneAudio clarifying the two questions I asked them.

The S17 Pro always works in class A (look elsewhere in this thread - Aune and others have already stated that). I also thought Violectric amps are class A but one of the reviewers of their latest amps clarified elsewhere in this thread that at least the V222 is class AB (I guess the others also should be). Burson is 5 to 6 times the cost of a S17 and uses passive cooling inside the chassis (fans), which is a solution I also don't find particularly elegant.

Btw, I find that my Arya Stealth's sound better in 50ma (which is class A) and so probably your He1000 could also sound better in that mode (at least to my ears).

 

[davehutch]

The S17 Pro always works in class A (look elsewhere in this thread - Aune and others have already stated that). I also thought Violectric amps are class A but one of the reviewers of their latest amps clarified elsewhere in this thread that at least the V222 is class AB (I guess the others also should be). Burson is 5 to 6 times the cost of a S17 and uses passive cooling inside the chassis (fans), which is a solution I also don't find particularly elegant.

Btw, I find that my Arya Stealth's sound better in 50ma (which is class A) and so probably your He1000 could also sound better in that mode (at least to my ears).

That's good to hear, but I think the Arya Stealth and HE1000SE sound quite different to each other on different amps so it might not be a good indication. (going by various reviews if memory serves my right)
Burson Soloist 3XP is less than double the price of the Aune though and has no fan. Obviously they do make some massively expensive models too.

 

[stevedlu]

....

lol, if the TA-22 is hot then the S17pro is Molten Lava. It does get warm, a lot of circuitry crammed into a small space, has decent venting though.

 

[Majuto]

The S17 Pro always works in class A (look elsewhere in this thread - Aune and others have already stated that). I also thought Violectric amps are class A but one of the reviewers of their latest amps clarified elsewhere in this thread that at least the V222 is class AB (I guess the others also should be). Burson is 5 to 6 times the cost of a S17 and uses passive cooling inside the chassis (fans), which is a solution I also don't find particularly elegant.

Btw, I find that my Arya Stealth's sound better in 50ma (which is class A) and so probably your He1000 could also sound better in that mode (at least to my ears).

I think soundwise Aune is excellent amplifier and for my listenings about 95% is done with 50mA, which I preferred from the beginning. I guess it depends of one's headphones and taste also which one you prefer.
Inspired by discussion here I ordered a cooling thin laptop stand for 100 mA long listening sessions. My firmware is 5.2 and after testing I found that Aune heats up differently with 4-core and 16-core headphone cables, which is a thing that I couldn't expect to happen. So all in all this amp imo have only two minor reservations: the early production units vol scale is too coarse if DAC doesn't have vol adjustment, the heating up in 100mA isn't anyway a big problem. A fan is easy to use and very affordable.
Imo soundwise Aune is able to compete with amps even two or possibly even three times it's price. In this respect at least the hype is understandable and well deserved.

 

[MiguelP]

lol, if the TA-22 is hot then the S17pro is Molten Lava. It does get warm, a lot of circuitry crammed into a small space, has decent venting though.

Well, one of the reviewers (Zeus) measured the S17 Pro case temperature and it was 41 °C when the temperature indicated in the unit was 66 °C, so I assume that 43 °C should be around the maximum case temperature, before switching to 50ma and cooling down.

Headphonesty in their review of the Xduoo TA-22 indicates a maximum case temperature of 105 F which I think it's a bit more than 40°C.

So I guess that the difference between hot and molten lava is 3 °C?

 

[SmartCheetah]

Well, one of the reviewers (Zeus) measured the S17 Pro case temperature and it was 41 °C when the temperature indicated in the unit was 66 °C

Yeah, the sensor measures the hotspot around the heatsink.

 

[stevedlu]

Well, one of the reviewers (Zeus) measured the S17 Pro case temperature and it was 41 °C when the temperature indicated in the unit was 66 °C, so I assume that 43 °C should be around the maximum case temperature, before switching to 50ma and cooling down.

Headphonesty in their review of the Xduoo TA-22 indicates a maximum case temperature of 105 F which I think it's a bit more than 40°C.

So I guess that the difference between hot and molten lava is 3 °C?

I owned both, and put my hands on both, I could not leave my hand on the top of S17, I can leave it on the TA-22 all day.

 

[Marlowe]

2. According to this review by Soundnews, the amp uses Class-A/B for the 50mA mode - but if that isn't the case, I stand corrected.
Again, [Aune] can you please clarify whether the S17 Pro uses Class-A/B mode for 50mA?

Sandu at Soundnews (as well as Ichos, who said the same) are very good reviewers, but they got this wrong. Aune has already clarified this in this very thread (at least once, though I'm not searching for it) stating flatly that the S17 always operates in Class A mode whether it is in 50mA or 100mA mode.

Update: As you can see a few posts down, Aune now clarifies this point yet again.

 

[Erick Muller]

Same here. For me it was a great improvement coming from the K7, ST-Amp and EF-400.

But I'm interested to at least try the TA-22 to form my own opinion.

I was also considering the TA-22 before getting my S17.

 

[Erick Muller]

I find that the Mojo 2 works better between 2 and 3 V. Above 3V it starts clipping. The Chord Mojo 2 pairs wonderfully with the Aune S17 Pro (it's the combination I use). The only complaint I have is indeed the heating but it's not fair to compare with other brands that do not switch to a lower current to preserve the components. When you're saying that other class A amps do not get hot that's simply not true - what you meant is that you don't have a indication of their temperature and they don't lower the current above certain temperature (as far as we know).

Yep, the main issue with the S17 is that it's to transparent and it's telling you a lot of things that are happening inside the amp, something that the vast majority of amps don't do, specially at this price point. So given that this is probably the first fully discrete class-A amp for many people that are getting it, given is price point, the amp is giving you a lot of information about it's internal workings all the time and the OCD tendencies of audiophiles, this causes a lot of stress and anxiety.

 

[Erick Muller]

I owned both, and put my hands on both, I could not leave my hand on the top of S17, I can leave it on the TA-22 all day.

I can also leave my hand on top of my S17, I'm starting to think there was an issue with your particular unit, like it does get hot, but not so hot that you need to get off your hand immediately.