Fosi ZH3 Balanced Headphone Amp & DAC Review

[Whatsthephuss]

I have massiv problems with the RCA analog inputs. Going from the DX3pro with 5m cable to the RCA inputs to the other side of the room I get massive his. Speakers are ADAMS connected with XLR.

If I connect the cable with the PAII at the same location of the fosi and same power plug (but going into passive speakers) - here is no hiss at all.

Using different speakers with different amplifiers will not help you diagnose the problem imo

If you can use the Fosi as a preamplifier into the pa ii + passive speakers then you can attenuate the Fosi until you do not hear anymore noise. I found the range from 24-32 to be unusable with my most sensitive headphones due to noise, so it would have been nice to have the RCA input + RCA/XLR output measured here

 

[joqueval]

I have massiv problems with the RCA analog inputs. Going from the DX3pro with 5m cable to the RCA inputs to the other side of the room I get massive his. Speakers are ADAMS connected with XLR.

If I connect the cable with the PAII at the same location of the fosi and same power plug (but going into passive speakers) - here is no hiss at all.

Hello.
5 meters of RCA cabling may be excessive and a source of unwanted noise, especially if it's connected to other cables and transformers.
For these cable runs, the best option is XLR or try reducing the length of the RCA cabling by adjusting the position of the equipment.
I rarely use cabling longer than 2 meters.

 

[bungle]

The tone controls themselves have made this my favorite headphone amp

I agree. Earlier I said that I am using USC II on computer to do correction and eq. I still am, sometimes, but I found that USC II (from RealPhones), is not particularly well programmed. It seems to take constant 5-10% of CPU with 44.1kHz. But not only that, sometimes it is not fast enough and you hear it. And it is annoying. So I am currently using tone control of ZH3. With my Ollo X1 I prefer bass +3db (a couple of steps before it starts to get boomy, with some songs you could add a bit more, but not with others), treble +1db. I get quite close to what I had with USC II (with 50% harman emulation that I liked the best) without any glitches or excessive CPU usage.

 

[Lux Maldini]

There are many sources with default output level at 2 Vrms. I am wondering if it is necessary to attenuate the output to avoid clippings for using ZH3 as a preamp.

Hello, this picture shows the test parameters for ZH3 RCA input.

 

[Seen Space]

Hey, sorry, I'm a total dummy regarding headphone power requirements n amp specs, but I believe I just won this amp in their giveaway n so I was wondering if you guys thought that this would be too weak for HE6SE V2's? I've seen a bunch of conflicting info on it, with some posts saying they were fine with even weaker amps, but of course manyyy others stating the polar opposite, with the consensus (including the OP stating that seemingly much less power-hungry headphones required the volume to be at 75 on high gain) definitely making it seem like this likely wouldn't work?

General side-question about power requirements: so the Fosi amp says that it's 2.5W at 32ohms- does this tell me anything about the wattage at, in the HE6's case, 50ohms? Or would I really just have to specifically message them to ask what the output is at 50ohms?

Thank you! (n sorry for da noob questions)

 

[Whatsthephuss]

Hey, sorry, I'm a total dummy regarding headphone power requirements n amp specs, but I believe I just won this amp in their giveaway n so I was wondering if you guys thought that this would be too weak for HE6SE V2's? I've seen a bunch of conflicting info on it, with some posts saying they were fine with even weaker amps, but of course manyyy others stating the polar opposite, with the consensus (including the OP stating that seemingly much less power-hungry headphones required the volume to be at 75 on high gain) definitely making it seem like this likely wouldn't work?

General side-question about power requirements: so the Fosi amp says that it's 2.5W at 32ohms- does this tell me anything about the wattage at, in the HE6's case, 50ohms? Or would I really just have to specifically message them to ask what the output is at 50ohms?

Thank you! (n sorry for da noob questions)

I have the HE6SE V2, even with an 8db bass boost and -2db treble cut I can only make it to level 80 on medium gain before it’s too loud. And I typically listen very loud for short durations. What are you currently using to drive the HE6SE? They scale well with better amps imo but that has less to do with measured power output at a certain point and more to do with the way the current is delivered. Finding the “right” amp for the HE6SE is an expensive rabbit hole, but the power in the ZH3 is adequate and with the tone controls it sounds great! Congrats on winning the giveaway!

 

[jkim]

I have asked the manufacturer about the RCA input sensitivity.
It is claimed to have 0.775 Vrms.
Anyone can verify this ?

View attachment 482063
Hello, this picture shows the test parameters for ZH3 RCA input.

This basically tells that we don't want to take seriously whatever information a manufacturer customer service rep gives about device specs. Its input sensitivity (for lineouts) is definitely not 0.775 Vrms! Aargh.

 

[bungle]

This basically tells that we don't want to take seriously whatever information a manufacturer customer service rep gives about device specs. Its input sensitivity (for lineouts) is definitely not 0.775 Vrms! Aargh.

it is a cheap chinese thingy, reliable stuff, just go with adi2 and call it done, ;-). (can’t have both). I went with zh3, but if it ever lets me down, i have learn’d my lesson. I have had rme internal pci card and that was wonderful, now i wanted to go cheaper, not sure yet if rme would have been cheaper in a long run.

Still, you are absolutely right.

 

[fws]

I was not able to respond yesterday to @Whatsthephuss posts, thank you for the pics of the manual btw., but I think we now have it sorted out, with the table that @Lux Maldini provided showing likely where the rep mistakenly took 0.775Vrms from as the input sensitivity in his reported reply to @MANDEV1L .

In a "you are right, but" fashion, flip switches > knob based navigation

 

[Whatsthephuss]

In a "you are right, but" fashion, flip switches > knob based navigation

Good point. The Fosi is fun, but time will tell how long the UI lasts… the Fiio K7 has been rock solid for 2yrs and I expect it’ll last a long time

 

[Lux Maldini]

In the volume adjustment interface, double-click the knob to quickly switch between PO and AUX modes, and the LO mode will be automatically skipped. I hope this can help you.

Nice little device, love it, just be careful with the output options since selecting LO disables pre volume control for pure dac mode on XLR and RCA out and i choose it by accident and blasted my ears at max volume.

Output options:
PO= Headphones
LO= Pure dac mode(disables volume control for XLR/RCA)
AUX= XLR/RCA out with volume control

 

[Parky]

I don't know if this has been mention anywhere but this has a double click function when you are on the normal screen where you can change volume the double click function swaps you between po and aux even if you use it on lo it will only switch back and forth between po and aux. If you are in the menu system you can use the double click to get to the home screen were there is volume control and not have to wait the 10 seconds. Just thought I would share this.

 

[Whatsthephuss]

I previously reported noise with my ZH3 when using RCA in, PO out levels 24-32. Swapped the op amps and that noise is now totally gone. Does anyone else have noise from level 24-32 using RCA input (and no signal)? This was the only “fault” I could find with the unit, so happy that it’s gone. If I could just use EQ with the AUX + PO outputs this would be perfect…

 

[Elvom]

im having this issue in windows 11 when playing a new track, or video the sounds mutes for the first half second. I remember i had this same issue with another xmos device and used this thread to fix it: https://www.audiosciencereview.com/...os-driver-settings-for-no-cutoff-delay.25838/ however it doesnt seems to work anymore, anyone experiencing the same? any fix?
its like the dac goes into sleep for half a second when an audio track changes.

If i cant fix it ill be returning it, its driving me insane.

 

[Sheryl Nome]

@Fosi Audio

im having this issue in windows 11 when playing a new track, or video the sounds mutes for the first half second. I remember i had this same issue with another xmos device and used this thread to fix it: https://www.audiosciencereview.com/...os-driver-settings-for-no-cutoff-delay.25838/ however it doesnt seems to work anymore, anyone experiencing the same? any fix?
its like the dac goes into sleep for half a second when an audio track changes.

If i cant fix it ill be returning it, its driving me insane.

I have the same issue and fix in the thread didnt work too.
I think it could not be fixed unless fosi audio makes a new firmware\drivers update...

 

[Parky]

Which usb socket are you using on your device have you tried using different ones?

 

[Sheryl Nome]

I tried literally every port, type-C, A, 3.0, 2.0, USB hub, no hub, front ports, back ports. I have also 2 other DACs fiio k5 and shciit modi 3 both works fine. Modi3 is working as intended with ZH3 as amp through RCA ports.

I got a replay from fosi support, they said: "In order to bring customers a better listening experience, we added a 300ms mute function to prevent explosive and pop sounds.
Please set the sampling rate to 24bit/384kHz first. If the issue persists, kindly follow the steps in the attached guide to upgrade the software." And gave me archive with a firmware update. Id say 384khz kinda works, the first time i played win notif sound it did cut out but afterward—even after about 10 minutes of inactivity—it continued playing normally.

 

[Lux Maldini]

Yes, we have updated the new software, and many customers have already solved the problem of music disappearing before 300ms after updating the new software. If you need it, you can contact our customers to collect the firmware;

 

[Whatsthephuss]

Yes, we have updated the new software,

is it possible to update the software to include EQ on AUX output? Or is that a limitation in the hardware?

I’m using PO output 3.5mm to dual RCA as a current workaround, but would love to use XLR out with tone controls.

 

[Lux Maldini]

is it possible to update the software to include EQ on AUX output? Or is that a limitation in the hardware?

I’m using PO output 3.5mm to dual RCA as a current workaround, but would love to use XLR out with tone controls.

This is due to hardware limitations, RCA and XLR do not support EQ adjustment;