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Preview: Monolith by Monoprice Desktop THX Headphone Amp & DAC

amirm

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#1
This is an early look of the Monolith by Monoprice Desktop Headphone Amplifier and DAC with THX amplification technology. The unit was kindly purchased by a forum member and drop shipped to me. And that is where the trouble began but more on that later. The Monoprice THX amp and DAC retails for USD $480.

The Monoprice THX amp and DAC has the same design language of other "monolith" units which translates to a serious look. There is brushed metal on front and very shiny and glossy enclosure which instantly shows fingerprints:

Monoprice Monolith Desktop Headphone Amplifier and DAC Review.jpg


Let's backtrack a bit. I have ordered three products from monoprice. The first one never came and I only found out about it a few months later. I then ordered two other products from them both of which were sent to a remote neighbor. Their street and house number are one digit off from us. Hard to imagine how someone could be this bad at reading addresses yet be in delivery business.

Worried that this unit would also face the same fate, I contacted the carrier and monoprice. With the latter, I read them the riot act for sending the last shipments to wrong address. No response came back. The carrier sent me a form response a couple of days later saying "we will get back to you." Well, they didn't and today got notification that the package was delivered at the front door. Searched everywhere and no sign. Called the carrier and they started to investigate. A few phone calls later and then neighbor calls and says the package is once again delivered to her. :( Thankfully it was double boxed or it would have been soaked in the rain.

I unpack the unit and find no manual of any type -- just a code to put in online to find it. I know we have moved away from paper but come on, for a $500 device, I expect a little cheat sheet on how to power the unit on. Yes, how to power it. Look at the front panel: there is no indication of how you turn it on! Fumbling I hit the enter button and I see the monoprice log and the unit lights up.

I hook up a USB cable to it, select that input and run a quick dashboard test. I get to SINAD of 107 in best case scenario. Where is that output you ask? Well, I usually run a few quick tests before doing a formal review and I don't save those. I went on to test output power and with 300 ohm, and single-ended, I get half the rated power before clipping (and less than Topping DX3 Pro). I then test 33 ohm, and here I get about a watt of power which is decent.

I thought I test the amplifier section by itself so I hook up a set of analog cables to its inputs. In the midst of switching things around, the protection circuit kicks in which is fine. But on the second instance this happened, the unit shut itself off. Hmmm. This is never a good sign. I turn it back on and now it is acting crazy. Menus work but changing the volume causes it to update the new value 0.5 dB every few seconds! Changing inputs no longer works as you see from the stuck "RCA Line" in the above picture. Factory reset does nothing.

There is an about menu so I selected that and see this:

Monoprice Monolith Desktop Headphone Amplifier and DAC Beta Firmware.jpg


0.82 beta? Really? With all the delay in production of this unit they couldn't finish the firmware?

Seeing the dismal usability of the firmware, my suggestion is for them to throw it all out and start over. It is maddening to navigate. Why isn't there a single button press for changing inputs? Once you go into menus, the rotary volume control goes through different options. But when you go into settings, the enter button does that! Why or why? Between it crapping out and poor usability I am tempted to throw it into the bay. But then it is not mine so I better not do that. :)

And oh, the purpose of messing with it was that I was getting the two channels completely out of phase with each other when feeding it analog input! I ran out of options with the thing breaking before trying everything. I doubt the issue is at my end though.

Back to functionality, any desktop product in this range should have a remote control for volume so that you can use it in your equipment rack.

Conclusions
I was all excited to get this review out quickly for you all. But the company didn't allow it. Between poor delivery, customer service, firmware functionality and reliability, I am not sure I have any motivation left to test the product anymore. And can you imagine my mood if they replace this and it goes to the neighbor again? She was ready to shoot me had it not been for the joyous holiday mood!

The bit of performance that I did measure was good but not exceptional. At nearly $500, that is not acceptable. You can get excellent $100 DACs and pair them with the Massdrop THX 789 or JDS Labs Atom and be in business for less than what this unit costs. And they would be a lot easier to use.

Anyway, I feel bad for the owner who actually lives in Europe and ordered this just for the good of the community. I think I am going to ask him to get a refund instead of replacement.

My suggestion is to buy the Massdrop THX, JDS Labs Atom or Neurochrome HP-1 if you need high performance headphone amplification and a DAC of your choice. Otherwise, there are excellent all-in-one choices like Topping DX3 Pro which cost less than half of this unit.

-----
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Veri

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#4
Not only could they not finish the firmware, there is also no USB driver available. Maybe this will come sooner or later but looking at its current quality I wouldn't even count on it.

Besides that, all analog input goes into an internal ADC to make the EQ and/or DIRAC work. That's probably where @amirm's out of phase problem came into play. I was not optimistic this was going into an ADC just to go into its DAC again but told myself, how can they screw this up? Seemed straight-forward enough but well, I guess they did screw it up. God damn I really wanted to love this device.

Guess I'll be waiting for @March Audio's amp. Between the THX AAA, the Neurochrome and it, March's seems like the lowest distortion one, hope amir's tests it once it hits production :)
 
Last edited:

amirm

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#5
Besides that, all analog input goes into an internal ADC to make the EQ and/or DIRAC work.
Ah, here I thought that input would be analog and just go to the THX amp. Bummer.
 

Veri

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#6
Ah, here I thought that input would be analog and just go to the THX amp. Bummer.
Once I learned of that I thought it wouldn't have to necessarily be a problem, expecting the same testing and Q/A of the massdrop one. I guess I expected too much!
 

amirm

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#7
Forgot to note this in the manual:

1543304866361.png


Say what??? Prolong its life? What happens to it if you don't follow that? Something wears out?
 
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#9
Dodged a bullet on this one apparently, I nearly ordered it but decided to just go with the Massdrop one instead. Made the right call I guess. Had high hopes for this one as it seemed Andrew Mason had some involvement with it but Monoprice managed to screw it up as they are want to do.


As usual thank you for making me feel better about my purchases Armirm!
 

March Audio

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#10
Guess I'll be waiting for @March Audio's amp. Between the THX AAA, the Neurochrome and it, March's seems like the lowest distortion one, hope amir's tests it once it hits production :)
He will be :)

Just re-laying out the PCB

Capture.jpg
 
Last edited:
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#13
That sucks bro. But in the future lets just say if you were to somehow get a perfectly working unit that was sent to you at the correct address and time with an updated firmware .Would you reconsider reviewing it ?
 

Thomas savage

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#15
Forgot to note this in the manual:

View attachment 18099

Say what??? Prolong its life? What happens to it if you don't follow that? Something wears out?
Yea it can cause a issue , Iv blown a few fuses on kit turning it off then on again without letting the caps drain.
 

restorer-john

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#16
Yea it can cause a issue , Iv blown a few fuses on kit turning it off then on again without letting the caps drain.
At the end of the day it is poorly designed gear that would do that. Most competently designed HiFi gear has AC sense which will disconnect the relays (speakers) instantly (<5 cycles), on loss of power and discharge the main caps via parallel connected bleeder resistors. Turning it back on prior to caps discharging isn't an issue with 99% of HiFi gear and neither it should be, as the current draw on restart is less than a cold start (discharged fully).

The UPC1237HA and other 'protector' ICs are foolproof in that regard and have been the standard for decades. What they are using these days for low level (<4V) I don't know, but at those levels, no fuses should be blowing on a quick turn off/on cycle.
 
Last edited:

restorer-john

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#17
Just for the record, technicalities apart, that brushed aluminium finish looks awful.
I think it may be the light and the camera. I can't believe it actually looks like that. Anodizing needs a good surface.
 

jsmiller58

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#18
This is an early look of the Monolith by Monoprice Desktop Headphone Amplifier and DAC with THX amplification technology. The unit was kindly purchased by a forum member and drop shipped to me. And that is where the trouble began but more on that later. The Monoprice THX amp and DAC retails for USD $480.

The Monoprice THX amp and DAC has the same design language of other "monolith" units which translates to a serious look. There is brushed metal on front and very shiny and glossy enclosure which instantly shows fingerprints:

View attachment 18096

Let's backtrack a bit. I have ordered three products from monoprice. The first one never came and I only found out about it a few months later. I then ordered two other products from them both of which were sent to a remote neighbor. Their street and house number are one digit off from us. Hard to imagine how someone could be this bad at reading addresses yet be in delivery business.

Worried that this unit would also face the same fate, I contacted the carrier and monoprice. With the latter, I read them the riot act for sending the last shipments to wrong address. No response came back. The carrier sent me a form response a couple of days later saying "we will get back to you." Well, they didn't and today got notification that the package was delivered at the front door. Searched everywhere and no sign. Called the carrier and they started to investigate. A few phone calls later and then neighbor calls and says the package is once again delivered to her. :( Thankfully it was double boxed or it would have been soaked in the rain.

I unpack the unit and find no manual of any type -- just a code to put in online to find it. I know we have moved away from paper but come on, for a $500 device, I expect a little cheat sheet on how to power the unit on. Yes, how to power it. Look at the front panel: there is no indication of how you turn it on! Fumbling I hit the enter button and I see the monoprice log and the unit lights up.

I hook up a USB cable to it, select that input and run a quick dashboard test. I get to SINAD of 107 in best case scenario. Where is that output you ask? Well, I usually run a few quick tests before doing a formal review and I don't save those. I went on to test output power and with 300 ohm, and single-ended, I get half the rated power before clipping (and less than Topping DX3 Pro). I then test 33 ohm, and here I get about a watt of power which is decent.

I thought I test the amplifier section by itself so I hook up a set of analog cables to its inputs. In the midst of switching things around, the protection circuit kicks in which is fine. But on the second instance this happened, the unit shut itself off. Hmmm. This is never a good sign. I turn it back on and now it is acting crazy. Menus work but changing the volume causes it to update the new value 0.5 dB every few seconds! Changing inputs no longer works as you see from the stuck "RCA Line" in the above picture. Factory reset does nothing.

There is an about menu so I selected that and see this:

View attachment 18097

0.82 beta? Really? With all the delay in production of this unit they couldn't finish the firmware?

Seeing the dismal usability of the firmware, my suggestion is for them to throw it all out and start over. It is maddening to navigate. Why isn't there a single button press for changing inputs? Once you go into menus, the rotary volume control goes through different options. But when you go into settings, the enter button does that! Why or why? Between it crapping out and poor usability I am tempted to throw it into the bay. But then it is not mine so I better not do that. :)

And oh, the purpose of messing with it was that I was getting the two channels completely out of phase with each other when feeding it analog input! I ran out of options with the thing breaking before trying everything. I doubt the issue is at my end though.

Back to functionality, any desktop product in this range should have a remote control for volume so that you can use it in your equipment rack.

Conclusions
I was all excited to get this review out quickly for you all. But the company didn't allow it. Between poor delivery, customer service, firmware functionality and reliability, I am not sure I have any motivation left to test the product anymore. And can you imagine my mood if they replace this and it goes to the neighbor again? She was ready to shoot me had it not been for the joyous holiday mood!

The bit of performance that I did measure was good but not exceptional. At nearly $500, that is not acceptable. You can get excellent $100 DACs and pair them with the Massdrop THX 789 or JDS Labs Atom and be in business for less than what this unit costs. And they would be a lot easier to use.

Anyway, I feel bad for the owner who actually lives in Europe and ordered this just for the good of the community. I think I am going to ask him to get a refund instead of replacement.

My suggestion is to buy the Massdrop THX, JDS Labs Atom or Neurochrome HP-1 if you need high performance headphone amplification and a DAC of your choice. Otherwise, there are excellent all-in-one choices like Topping DX3 Pro which cost less than half of this unit.

-----
If you like this review, please consider donating funds using Patreon (https://www.patreon.com/audiosciencereview), or upgrading your membership here though Paypal (https://audiosciencereview.com/foru...eview-and-measurements.2164/page-3#post-59054).
Wow, your neighbor has some real people skills... I live up in the foothills east of Redmond and while people live up there at least in part for the privacy and isolation, most are at least tolerant of others...

And, yeah, thanks for the observations and impressions even before measurements... the 788 was on my list, but, no longer. Maybe there will be a v2 one day...
 

Thomas savage

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#19
At the end of the day it is poorly designed gear that would do that. Most competently designed HiFi gear has AC sense which will disconnect the relays (speakers) instantly (<5 cycles), on loss of power and discharge the main caps via parallel connected bleeder resistors. Turning it back on prior to caps discharging isn't an issue with 99% of HiFi gear and neither it should be, as the current draw on restart is less than a cold start (discharged fully).

The UPC1237HA and other 'protector' ICs are foolproof in that regard and have been the standard for decades. What they are using these days for low level (<4V) I don't know, but at those levels, no fuses should be blowing on a quick turn off/on cycle.
Yea maybe we should separate ‘HiFi ‘ and ‘ high end ‘ Audio here lol
 
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