Monoprice Monolith Desktop THX Amp/DAC (#24459) - Impressions Thread

[Packdemon]

I don’t think any measurement, with regards to an amp are useful. Possibly wattage if you have hard to drive headphones. Beyond features, which tend be a DAC function and not the amp, most amps will sound fine with most headphones. Sometimes pairing matters, so if you have god and or sensitive hearing, the only way to know if a certain combination of equipment will work for you is to listen to it. Most people here put way too much stock in amps and DACs. There are a few that claim to be able to very subtle differences between models, and for for them, it might matter between $4000 amp. For the vast majority of listeners, the headphones make the most difference to the sound, assuming a decent amp and DAC and good source material.

Obviously the draw for this amp is Dirac.

Why crap on an amp that you haven't heard before? Or have you?

 

[Allanmarcus]

Why **** on an amp that you haven't heard before? Or have you?

What? I’ve said nothing about this amp other than the draw of the amp, the thing that makes it interesting, is the Dirac.

 

[Packdemon]

What? I’ve said nothing about this amp other than the draw of the amp, the thing that makes it interesting, is the Dirac.

Wait, that was runssical. Nvm, lol

 

[runssical]

I wouldn't be surprised if Monoprice pulls the plug on their THX partnership. Something is up.

The Massdrop THX amp

Wait, that was runssical. Nvm, lol

Looks like my comment stirred things up on here.

I just think we need to forget about this DAC. With another 5 week delay after a 1 month delay just a couple months ago there is little reason to believe that this device is ever coming out.

Keep in mind that Monoprice also raised the expected price from $399 to $479 since the PR in Fall 2017.

This is simply a disaster.

I think the Cavalli products look promising. The upcoming Cavalli balanced amp could be a winner. The budget Liquid Spark has good reviews thus far. So...promising.

I want to point out that the AKM DAC chips in this Monoprice DAC are the cheapies that AKM markets for application in Soundbars and portable battery powered Bluetooth speakers. It's not their flagship chips. The chips are lower power draw and the page at AKM website touts them as ideal for "portable" devices, not audiophile desktop devices. Their flagship is marketed for audiophile components such as desktop DACs, CD players, ect.

In case I have to I'll just remind everyone that THX has no credibility or reputation in product segment. This year is their first crack at getting these AAA modules into consumer and audio enthusiast products. I liken THX to Bose's "soundwave" gimmickry. Count me as skeptical.

Just to drill home how mediocre this Monolith DAC/Amp is, the manual (available on the product page) lists the power output as 1550mW x 2 into 16ohm is weak as heck for a balanced desktop amplifier. The little dinky Magni 3 outputs 3,000mW x 2 into 16ohm.

Pass, pass, pass!

 

[mattris]

You certainly have your doubts, don't you?

Within the Questions/Answers tab on the product page:

October 15, 2018
"Is this gonna be released soon? It's been delayed for a long time. Any issues with the production?"

From Monoprice Staff:
Yes it is! It is actually on its way! There haven't been any delays due to "issues", more with general parts availability. The switch to the AKM 4493 DAC from the 4490 was the main culprit in the hold up.


From THX AAA tech engineer:
It contains dual THXAAA-788 stereo amplifier modules configured to create a fully balanced bridged stereo output.



Obviously, some corners were cut to achieve this price-point, which is still more than reasonable. Even without a super-powerful amplifier, I expect its sound quality will be thoroughly impressive... and hopefully, the Dirac Sensaround mode will, as well.

 

[mandrake50]

I wouldn't be surprised if Monoprice pulls the plug on their THX partnership. Something is up.

The Massdrop THX amp


Looks like my comment stirred things up on here.

I just think we need to forget about this DAC. With another 5 week delay after a 1 month delay just a couple months ago there is little reason to believe that this device is ever coming out.

Keep in mind that Monoprice also raised the expected price from $399 to $479 since the PR in Fall 2017.

This is simply a disaster.

I think the Cavalli products look promising. The upcoming Cavalli balanced amp could be a winner. The budget Liquid Spark has good reviews thus far. So...promising.

I want to point out that the AKM DAC chips in this Monoprice DAC are the cheapies that AKM markets for application in Soundbars and portable battery powered Bluetooth speakers. It's not their flagship chips. The chips are lower power draw and the page at AKM website touts them as ideal for "portable" devices, not audiophile desktop devices. Their flagship is marketed for audiophile components such as desktop DACs, CD players, ect.

In case I have to I'll just remind everyone that THX has no credibility or reputation in product segment. This year is their first crack at getting these AAA modules into consumer and audio enthusiast products. I liken THX to Bose's "soundwave" gimmickry. Count me as skeptical.

Just to drill home how mediocre this Monolith DAC/Amp is, the manual (available on the product page) lists the power output as 1550mW x 2 into 16ohm is weak as heck for a balanced desktop amplifier. The little dinky Magni 3 outputs 3,000mW x 2 into 16ohm.

Pass, pass, pass!

From AKM
"Dec 8, 2017 - AKM releases AK4493, upgrade to the AK4490, the best selling Premium High-end DAC, ... As an upgrade from the AK4490EQ"
and

"Applications
High-end Audio, Professional Audio, AV Receivers, CD/SACD Players, Network Audio, USB DAC’s, USB Headphones, Sound Plates, Sound Bars, PA Equipment, Bluetooth Headphones, HD Audio, Voice Conference Equipment, IC Recorders, Measurement Instruments, Control Systems"

If you get half a watt into the impedance of your headphones it will be more than sufficient to cause hearing damage in most cases.
So what am I missing?

Of course I know nothing more about the device than anyone else here, but were I to try and belittle the device I would pick criteria that were one, accurate, and two would actually influence suitability for use.

BTW, I have been around the hobby for quite some time. It has been rare for any manufacturer to meet their initially announced schedule for a new product release on a brand new product.

I am not in a big hurry, so once the DAC/AMP has been out for a bit and there are some reviews, and if it lives up to the hype and is reliable, I will definitely pick one up.

 

[Sythrix]

Alright, score! Just got confirmation from the staff that the person who replied to me is the THX engineer. This was the staff's reply:

"
The gentleman that answered is the AAA tech engineer from THX. Obviously, we stand by his answer as we worked extensively with THX in bringing this product to fruition.
Hobie S Staff on Aug 24, 2018"

Recap:

My original question:

"OK, so the 788 isn't a true balanced amplifier... but you're putting two in. AND you're putting in two AKM 4493 DACs.

Are you putting two of these in to make it a balanced output? What is the reasoning behind using two of each of these units if the unit won't be balanced? Furthermore, why put a 4-pin XLR connector on the unit if it won't be balanced? You have a lot of clarifying to do Monoprice and I suggest you get someone who actually knows what they're talking about to answer all these questions, because they are not being answered with any clarity."

Answer (now confirmed to be the THX engineer):

" Incorrect. This Monoprice unit is truly balanced in & out. It contains dual THXAAA-788 stereo amplifier modules configured to create a fully balanced bridged stereo output. It also supports TRS unbalanced output.
The XLR-4 is present to permit balanced headphone connection."

The engineer who responded to my initial inquiry actually responded to my followup question (which I never actually showed since Hobie S from Monoprice staff answered for him). He must have logged in and saw it and decided to respond himself. We already know, but I thought everyone might want to see it from the horse's mouth, so to speak. Here is the comment and his reply

...and now, to continue:

My response to his answer (before I learned he was a THX engineer from Hobie S, Monoprice staff):

"Incorrect? What information do you have? Do you work for Monoprice? Because the only thing I've seen is a staff response that told someone that it was not a truly balanced output (that response seems to be gone now), which prompted this question.

Also, during questioning over at Massdrop for the THX 789, on of the THX team stated that this DAC/AMP would not be truly balanced."
Tom T You on Aug 23, 2018

His answer today:

"I work for THX and have seen the schematic
The Monoprice desktop XLR-4 output IS truly balanced. There was an early miscommunication about how many 788 amplifiers were going to be included in the design. i.e. having balanced output requires more amplifiers than just single-ended output."
Andrew M on Oct 17, 2018

So that's it. Not really new information, just overwhelming confirmation. I still think this is just a bunch of vaporware at the moment... but at least it's balanced vaporware. Important stuff.

 

[Packdemon]

For me the measurement of noise floor matters. Want to hear your system's noise floor? Turn up your source (computer) and amplifier volume to max, go high gain, and watch a YouTube video with the YouTube control volume muted. Despite the video being muted it should be playing the amplified signal coming from your source.

All that noise is part computer, part DAC, and part amplifier. So it's good to have a quiet system.

 

[Allanmarcus]

For me the measurement of noise floor matters. Want to hear your system's noise floor? Turn up your source (computer) and amplifier volume to max, go high gain, and watch a YouTube video with the YouTube control volume muted. Despite the video being muted it should be playing the amplified signal coming from your source.

All that noise is part computer, part DAC, and part amplifier. So it's good to have a quiet system.

ok. what standard vendor provided measurement shows noise floor?

thanks for the tip. I just tired it, and I heard nothing!

 

[Packdemon]

ok. what standard vendor provided measurement shows noise floor?

thanks for the tip. I just tired it, and I heard nothing!

I've seen vendors list the noise floor before, but I'm not sure what the noise floor is for the 788.

 

[runssical]

You certainly have your doubts, don't you?

Within the Questions/Answers tab on the product page:

October 15, 2018
"Is this gonna be released soon? It's been delayed for a long time. Any issues with the production?"

From Monoprice Staff:
Yes it is! It is actually on its way! There haven't been any delays due to "issues", more with general parts availability. The switch to the AKM 4493 DAC from the 4490 was the main culprit in the hold up.


From THX AAA tech engineer:
It contains dual THXAAA-788 stereo amplifier modules configured to create a fully balanced bridged stereo output.



Obviously, some corners were cut to achieve this price-point, which is still more than reasonable. Even without a super-powerful amplifier, I expect its sound quality will be thoroughly impressive... and hopefully, the Dirac Sensaround mode will, as well.

The portable THX DAC/Amp also has dual AK D/A chips and dual THX modules. Despite this factf ac portable is listed in the manual as only having SE output. Not balanced.

I'm not an engineer but I know there are differences in balanced topologies. There is a right way to do it and a half-arsed way.

 

[runssical]

I think Monoprice is no where close to stocking the two THX DAC products. They posted manuals for both units back in September but ommited an output impedance spec, one of the most crucial specs for any amplifier.

Translation: these dacs are still vaporware and not even in production yet. THX and/or Monoprice don't know what theyret doing.

Maybe they bit off more than they could chew with these combo DAC/AMP units and are having difficulty with the balanced configuration?

 

[Packdemon]

ok. what standard vendor provided measurement shows noise floor?

thanks for the tip. I just tired it, and I heard nothing!

You're lucky, where I live we have a lot of Em noise and my house doesn't have the cleanest power. I do own a power conditioner to clean up the sound from the power of my house, but the device itself produces sound just from being on so there's almost no point in using it. I could try throwing a blanket to absorb some of the sound, but I'm worried it might overheat.

 

[Asahi Templar]

Ok, lets see if we can put some of the naysaying to rest.

First off the Desktop version of the Monoprice THX DAC/AMp will be fully balanced.

The reason people are claiming that its not is because the original design of this amp/dac was not balanced.

Originally they were planning to use only a single AKM 4490 and a single THX 788 amp.

Someone asked Andrew Mason, the THX engineer, about the Monoprice unit when he was answering questions about the Massdrop 789 amp. He answered that the Monoprice was not fully balanced because the 788 as as single unit is not balanced. This was before Monoprice redesigned the unit.

Now the version that they are making is a fully balanced unit. They redesigned it to use TWO 788 THX amp modules as well as two AKM 4493 DAC chips. THis is a hardware balanced configuration now and Andrew Mason confirmed it in the questions and answers section of the monoprice website.

If you connect headphones to it using a XLR cable, you will have a fully balanced connection.

One should keep in mind, that 6.5mm/3.5mm connectors are not balanced on the desktop amp or the portable amp. If you are connecting via that port you are not getting a balanced connection.

The reason that the Portable unit says it is single ended only, is because it does not have a balanced output. Its a hardware balanced setup outputting as single ended.

In other words, the desktop unit is capable of a full balanced connection but the portable unit is not.

The output impedeance of a THX 788 amp is less than 0.05 Ohms at 1 kHz. according to Andrew Mason, who again answered this in the Q and A section. Both the portable and desktop unit should have this impedance.

The manual they released is likely an early version as it has some obvious omissions. The manual claims that the desktop unit is only capable of 192khz max frequency, but this is not true as the staff have already answered it can go up to 768khz and DSD 512 via USB. SO basically they forgot to give the specs for USB in the manual a well as output impedeance and even output power is not really listed correctly as it will be different for single ended and xlr outputs.

AS far as the output power goes, 1.5W into 16ohms is more than enough to drive the vast majority of headphones on the market to earbleed levels and if you are connecting via xlr that output should double to 3W into 16 ohms which will be good enough for roughly 98% of headphones out there. Only ones I can think of offhand it couldnt power would be some of the crazy Hifiman cans like HE6 or Fostex RP headphones if you are of the needs 6 watts mentality (I am not).

Realistically however, the desktop unit will live or die on its dacs merits, as there is no reason to buy it just for the amp section when you can get the Massdrop version for cheaper as its more powerful and likely a better performer. If it can pull of its full feature set, its gonna be a hell of a value. To my knowledge, there is nothing else that offers a built in parametric EQ and surround DSP in fully hardware balanced configuration with a stellar built in amp for under 1000 dollars.

 

[Allanmarcus]

ok. what standard vendor provided measurement shows noise floor?

I'm gonna take a crack an answering my own question.

I believe the answer is Signal to Noise ratio (SNR).

The Magni's is 108db
The Monoprice THX amp is >120db

From what I understand, anything over 90db is inaudible.

Also, crosstalk is important.
The magni is -70db
The Monoprice is: <100db

The mono price amp's measurement doesn't make any sense, as the lower the better. I believe -30 or better (lower) is desired. A cross talk of positive 100 is horrible. I can only assume this is a typo in the specs. Let's assume they meant <-100db. Still, both amps have inaudible crosstalk.

So, my point? from the posted specs, the magni is just a good as the THX amp. Do they sound the same? probably not, although the differences are probably minute (as in very small)

Any decent solid state amp that doesn't color the sound should sound pretty much the same to any other decent solid state amp that doesn't color the sound. In math, one would refer to the Symmetric and Transitive axiom's. What makes this amp really interning is the Dirac.