[ecwl]

Could you please explain why this is? Which class of power amp is required to reap most benefits from Qutest?

For years I've enjoyed my 2Qute (through an MFA passive preamp) with Ncore NC400 class D power amps. I listen to 95% classical music so enjoy the 'cleanliness' of the system. I'm not looking for euphonic distortion.

I've just ordered a Qutest, (looking forward to trying the 1V output option with my MFA to minimise attenuation) so I'm reading through this excellent thread for some education. Thanks in advance for your help.

JRiver->2Qute->MFA->Ncore->Audiovector

There are many reasons why Chord DACs sound great. But two of the basics are that first, the original 44.1kHz recording is upsampled to 705.6kHz with greater accuracy for analog reconstruction than other DACs. Afterwards this 705.6kHz signal is further upsampled to 10-elements at 104MHz so that the ultra-high-frequency switching can reconstruct the analog signal as faithfully as possible. By using such a high sampling rate, it allows for Chord DACs to reconstruct transients (loud and soft) much more accurately.
The problem with Class D amplifier is that they operate usually in the 450kHz-500kHz range. So the Class D amplifier switching frequency is not very high and is significantly lower than the WTA filter upsampling rate and the switching frequency of the pulse array DAC elements. As a result, the more accurate transient analog waveforms coming out of Chord DACs would be slightly distorted in the time domain by the Class D amplifier leading to transients that are not as accurately as the Chord DACs can provide.
There is no doubt in my mind that nCore is the best Class D amplifiers out there. If you're going to use a class D amplifier, I think nCore is definitely the way to go as it is the most neutral and beautiful sounding class D amplifiers out there. However, if you are to pair a Chord DAC with a neutral class A or AB amplifier, you will find that you can hear improved timbre and transient accuracy that you didn't realize your DAC is capable of. From my end, I think amplifiers such as Benchmark AHB2, Bryston latest generation of cubed amplifiers and Chord's own Etude and Ultima amplifiers would fit the bill for people looking for neutral sounding amplifiers that can show off the Chord DACs even more. That said, there are many other reasons why people want to use nCore amplifiers and ultimately, if that's what you like and want to settle on, you'll still get more out of your Qutest for sure.

 

[David M H]

There are many reasons why Chord DACs sound great. But two of the basics are that first, the original 44.1kHz recording is upsampled to 705.6kHz with greater accuracy for analog reconstruction than other DACs. Afterwards this 705.6kHz signal is further upsampled to 10-elements at 104MHz so that the ultra-high-frequency switching can reconstruct the analog signal as faithfully as possible. By using such a high sampling rate, it allows for Chord DACs to reconstruct transients (loud and soft) much more accurately.
The problem with Class D amplifier is that they operate usually in the 450kHz-500kHz range. So the Class D amplifier switching frequency is not very high and is significantly lower than the WTA filter upsampling rate and the switching frequency of the pulse array DAC elements. As a result, the more accurate transient analog waveforms coming out of Chord DACs would be slightly distorted in the time domain by the Class D amplifier leading to transients that are not as accurately as the Chord DACs can provide.
There is no doubt in my mind that nCore is the best Class D amplifiers out there. If you're going to use a class D amplifier, I think nCore is definitely the way to go as it is the most neutral and beautiful sounding class D amplifiers out there. However, if you are to pair a Chord DAC with a neutral class A or AB amplifier, you will find that you can hear improved timbre and transient accuracy that you didn't realize your DAC is capable of. From my end, I think amplifiers such as Benchmark AHB2, Bryston latest generation of cubed amplifiers and Chord's own Etude and Ultima amplifiers would fit the bill for people looking for neutral sounding amplifiers that can show off the Chord DACs even more. That said, there are many other reasons why people want to use nCore amplifiers and ultimately, if that's what you like and want to settle on, you'll still get more out of your Qutest for sure.

Thank you very much for your comprehensive and informative reply. I'll start auditioning other amps once I have the Qutest installed.

I also run the 2Qute into a Trilogy class A HP amp driving HD800, a combination that also sounds great to me. But I note Rob Watts saying that's not ideal either. Maybe I'm confusing the issue. Maybe that's more to do with missing the benefit of integration of DAC and HP amp in one product. Perhaps I should have just bought a Hugo 2!

 

[ecwl]

Thank you very much for your comprehensive and informative reply. I'll start auditioning other amps once I have the Qutest installed.

I also run the 2Qute into a Trilogy class A HP amp driving HD800, a combination that also sounds great to me. But I note Rob Watts saying that's not ideal either. Maybe I'm confusing the issue. Maybe that's more to do with missing the benefit of integration of DAC and HP amp in one product. Perhaps I should have just bought a Hugo 2!

Rob Watts makes a lot of comments about optimal playback from his perspective. I think his comments on 2Qute/Qutest + Trilogy HP amp are due to a number of factors:
1) It is unclear whether Trilogy's optimal input voltage is 3V (which is what 2Qute provides). It might perform better at 2V/1V which you can set with Qutest
2) Trilogy has a passive? preamp volume control and the sophisticated digital volume control from Chord Hugo 2/TT2/DAVE is always going to be more transparent than any analog preamp (active or passive). Note this is not true for all DACs because some DACs' digital volume control is not sufficiently sophisticated or the DACs themselves have too poor low-level linearity to allow for low volume output which is why those DACs tend to sound better with preamps.
3) A lot of class A amp actually has high levels of 2nd or 3rd harmonic distortions by design. The sound can often sound more euphonic.
4) A lot of amps have a lot of high frequency distortions.
So it is true that from Rob Watts' perspective, if your only system is DAC + amp + HD800, Hugo 2 + HD800 would theoretically be more optimal.
However, I'm a realist having played with audio products and upgraded many times and met many friends/audiophiles with different musical preferences. We all accumulate our gear in different ways and sometimes our favourite music benefits from some euphonic distortion. Who am I to say one system is theoretically suboptimal when the owner is enjoying his/her music tremendously.
From what I'm hearing and assuming, I'm assuming that you use the MFA to your nCore because you also listen to vinyl? Or maybe you have a home theatre/TV system connected to the MFA too so Chord 2Qute/Qutest is not your only source. Moreover, I personally don't think Hugo 2 is really as great as a desktop DAC because of the inclusion fo the battery and Hugo TT2 is just really expensive.
So given you have a headphone setup with the HD800, you have a speaker setup that probably includes vinyl or a different source, I think Qutest is probably the optimal upgrade for you.
I suspect once your Qutest arrives, what you'll notice is that music sounds a bit more transparent with more rhythmic and timbral accuracy off the Trilogy + HD800 vs the nCore + Audiovector. You can always decide whether you want to upgrade the nCore after enjoying the Qutest for a few months first.

 

[David M H]

ecwl, thank you again for another interesting post.

Your assumptions make sense, but are actually wrong. I won't derail this thread by discussing my system much but the DAC is my only source. I ended up with the MFA as an attenuator only because of its minimal influence. I might have a complete system rethink.

 

[ecwl]

ecwl, thank you again for another interesting post.

Your assumptions make sense, but are actually wrong. I won't derail this thread by discussing my system much but the DAC is my only source. I ended up with the MFA as an ettenuator only because of its minimal influence. I might have a complete system rethink.

Fair enough. I think I would suggest the following.
Upgrading from 2Qute to Qutest is a complete no brainer. I recommended a local friend to do so and he was absolutely ecstatic with no regrets.

Switching from Qutest + Trilogy amp to Hugo 2 is a more iffy proposition as different people have different sonic preferences so there is no guarantee that you’ll like the “upgrade”. If you’re upgrading directly to Hugo TT2, then I strongly suspect you can do it blind and you’ll prefer the sound over Qutest + Trilogy.
I suspect if you go from Qutest + PVC to Hugo 2 into the nCore, while the sound might be better you might not like the ergonomics of the Hugo 2 being plugged into the wall all the time. Whereas if you go straight to TT2, I doubt you’ll regret it, even if you do it blindly.

So my strong recommendation is that if you ever decide to try the Hugo 2, you need a home demo or a friend to lend you theirs in your home environment for at least a few days to decide if you really want to go in this direction. But of course, if possible, you should audition TT2 if that’s an upgrade you’re interested in.

Keep in mind, as you said, PVC is the most transparent analog volume control you can get. If I were you, I would just enjoy the Qutest for at least 6 months before exploring other options. And as I said before, I would also choose to upgrade nCore next if possible over Hugo 2 or TT2.

 

[Reactcore]

ecwl, thank you again for another interesting post.

Your assumptions make sense, but are actually wrong. I won't derail this thread by discussing my system much but the DAC is my only source. I ended up with the MFA as an ettenuator only because of its minimal influence. I might have a complete system rethink.

Hi! Be sure u try driving your HP ditect out of Qutest. I also use a 800 which with 300ohm is perfectly suited. Im controlling my vollume digitally with foobar. No amp.. no loss. Qutest has actually a powerful amp on board. I made a simple rca to jack adapter for it.

 

[ecwl]

Hi! Be sure u try driving your HP ditect out of Qutest. I also use a 800 which with 300ohm is perfectly suited. Im controlling my vollume digitally with foobar. No amp.. no loss. Qutest has actually a powerful amp on board. I made a simple rca to jack adapter for it.

Keep in mind though that Qutest doesn't have the 2nd-order analog noise shaper that Hugo 2, TT2 & DAVE have because it wasn't designed to drive headphones. As a result, depending on the headphone impedance load, you can get more high frequency distortions without this noise shaper. But if it works for your HD800, it should work for others. It then comes down to make sure the Qutest doesn't accidentally wreck the headphones with too much voltage. One just has to be super careful.
The other issue is how good the digital volume control is from the source. Rob Watts always recommends using Chord DACs' own digital volume control which is as transparent as can be. I've definitely listened to some fairly transparent digital volume control from Roon or JRiver but even in JRiver, if you set the settings wrong, the digital volume control can sound significantly worse. I have to admit I have never tried to compare the top digital volume controls with Chord's own as I suspect Chord would always be superior if fed bit-perfect data. But I do think this setup is totally worth trying for people who are curious but careful and willing to take a small risk.

 

[David M H]

@ecwl: Yes, Chord tech support strongly advised me to always bypass JRiver volume control. Fairly obvious. Maybe Foobar is better, IDK.

I've known for some time that what I really want is a Hugo TT2. The price is off putting but I might later seriously reconsider everything, building a new system around the TT2.

Good advice is to live with Qutest for a several months before doing anything else.

@Reactcore: Interesting. Since your HD800 have obviously survived, I'll look into driving mine direct from the Qutest. 1V output? Thanks.

 

[Victorr]

Im controlling my vollume digitally with foobar. No amp.. no loss.

I don’t want to upset you, but in this operation there may be significantly more loss of sound quality than when using most headphone amplifiers.

 

[Jon L]

As a result, the more accurate transient analog waveforms coming out of Chord DACs would be slightly distorted in the time domain by the Class D amplifier leading to transients that are not as accurately as the Chord DACs can provide.

In the end, I believe it will come down to how much of subjective difference that "slight" distortion makes in real life. Having used NCore and IceEdge with Chord Qutest, I would still take those combo's over traditional SS class A/AB amps ANYWHERE near the price range of class D amps tried. Especially when it comes to speaker systems, the effect of room reflections and acoustics tend to overwhelm these differences IME.

 

[Reactcore]

I did (ofcourse) extensive compararisons wih my Questyle amp-qutest combo and almost regret i bought the quesyle. As for the voltage i have Qutest at 2 v. Yes i had some accidental max volumes but at 300ohm senns its no prob. I wouldnt try max with sensitive iems.
I have also placed buffer capacitors over the internal 8v feed to the OP stage.

 

[alekc]

I am thinking about more desktop solution stricrly for headphones. Should I go with Qutest, Hugo 2 or pay more and start with Hugo TT right away. My mobile dac/amp is Mojo and I love its warm sound.

As for USB islotation I already have iusb3 and igalvanic. I would preferably be using USB input and streaming from Tidal/Audirvana. CD transport can be a very distant future option. Any tips from long time Qutest users?

 

[Reactcore]

I am thinking about more desktop solution stricrly for headphones. Should I go with Qutest, Hugo 2 or pay more and start with Hugo TT right away. My mobile dac/amp is Mojo and I love its warm sound.

As for USB islotation I already have iusb3 and igalvanic. I would preferably be using USB input and streaming from Tidal/Audirvana. CD transport can be a very distant future option. Any tips from long time Qutest users?

All depends on your budget.. if u have the funds go for tt2 (not tt 1st gen) ull want it later anyway. If u own a good amp then qutest measured better than hugo2. its also newer so chord had time to improve its circuitry further.. not to mention the pricetag offcourse.

 

[alekc]

All depends on your budget.. if u have the funds go for tt2 (not tt 1st gen) ull want it later anyway. If u own a good amp then qutest measured better than hugo2. its also newer so chord had time to improve its circuitry further.. not to mention the pricetag offcourse.

Thank you @Reactcore for your input. The thing is that Hugo 2 can be bought with not that much more expensive price tag currently than Qutest. Hence my question. I don't think I want both. With Hugo TT the price tag gap is larger currently but I can wait a bit. On the other hand Hugo 2 is portable which applies to me since I am traveling a lot and while Mojo is great for both short and long trips (assuming you can recharge it somewhere in between) I like the idea of something bigger that I can take with me and use it on the desk in remote office or hotel.

Tough choice - I know but please help me out guys

 

[ecwl]

Thank you @Reactcore for your input. The thing is that Hugo 2 can be bought with not that much more expensive price tag currently than Qutest. Hence my question. I don't think I want both. With Hugo TT the price tag gap is larger currently but I can wait a bit. On the other hand Hugo 2 is portable which applies to me since I am traveling a lot and while Mojo is great for both short and long trips (assuming you can recharge it somewhere in between) I like the idea of something bigger that I can take with me and use it on the desk in remote office or hotel.

Tough choice - I know but please help me out guys

I would say the first decision point is whether you plan on using hard to drive headphones in the future (and how loud you listen to music). If you do, you probably should save up for TT2. None of my headphones are hard to drive so Hugo 2 is definitely the best bang for the buck. Sure, it’s not as desktop friendly but it works and you save on the headphone amp.
On the other hand, if you’re always going to use an external headphone amp with volume control, you might as well save money and commit to Qutest now. Because your headphone amp would limit how much more you’ll get out of using Hugo 2 or TT2 so Qutest becomes best bang for the buck.