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SMSL HO100 Review (Headphone Amp)

Rate this headphone amplifier:

  • 1. Poor (headless panther)

    Votes: 1 0.6%
  • 2. Not terrible (postman panther)

    Votes: 6 3.7%
  • 3. Fine (happy panther

    Votes: 34 20.7%
  • 4. Great (golfing panther)

    Votes: 123 75.0%

  • Total voters
    164

shinewu

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I am using one on my desk right now. I think in terms performance, it is super impressive. But it is also $50 more expensive than the $100 gang (Atom, Magni, or SMSL SH-6). What it does right are:
1) Built-in AC/DC, no more chunky plugs.
2) RCA and XLR inputs, 4.4 and 6.25 outputs, just what I need!
3) No other extras, such as pre-outs.

Another contender for me was SONCOZ QXA1. It can take USBC power, neat, but it has no 4.4 out. So, in the end, I went with SMSL HO100, can't be happier now.
 

Xyrium

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Nicely done, two of the SMSL knocking it out of the park lately.

The 14Hz muting...it's actually playing something that low, it says "you can't hear this anyway, so why bother?".

;)
 

SCG

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Using the HO100 as part of my desktop system and really enjoying this amp driving my closed back 38Ω M50x (with Amir's EQ) and 50Ω Monoprice open back planars (also EQ'd). Config is MB -> D30p -> Headphones, and never need the volume past 1/2 way, runs cool to the touch and is well built and was on sale for $134.00

Until this year mostly used class AB amps via RCA connections with built in DACs and now slowly switching over (starting with my desktop system) to high SINAD class D amps & external DACs all connected via XLR and WOW what an improvement! These high SINAD products combined with XLR connections on both my headphones and LS50M are completely silent between songs at any volume.

So now when I heard any noise on those remaster tracks I know that the noise is fully coming directly from the master tracks during the recording process and not my system, and where they have high SINAD baked into the recording process my system also reveals that.

When the music fades (or slams) to black it's absolute pure silence (and bliss) just like the big difference when I switched from LED to OLED TVs on the picture side of things. When it comes to sitting near-field or listening with a headphone amp I'm a convert to these high SINAD, great measuring, low cost, balanced connected devices.

Thanks Amir!!
 
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plikestechno

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Just got mine last weekend and am liking it alot. Did far too much research over the last couple of months, this showed up in the past month and decided that this was all I really needed. I was thinking of the HO200 at 424 Canadian right now on sale but I dont need the preamp functions. The HO100 is simple but its all i actually need.

For under 200 Canadian brand new, available in Canada with free next day delivery it checked all of my boxes including xlr ins from my topping d90 or gold note ph10 balanced outputs through to a 4.4mm trrs out for my hd650s and internal power supply with three prong cord as I had a spare audioquest nrg z3 kicking around.

It definitely opened up the sound of my hd650s so it wasnt as cluttered, muddy and veiled as my previous simple cmoy amp and sounded great with my k712pros. Despite my best efforts i couldnt make the hd650s distort. High setting at about 2 oclock through the balanced ins and outs were as high as I could go without thinking i was going to blow my ears off. K712pros seem to be less amp dependant but this was a big step up for my hd650s and really made them stand out compared to cheaper amps that ive had before.

I’m sure something better and cheaper than this will come out next week because thats how it goes with these companies but for now this is definitely the best bang for buck out there in a headphone amp IMHO.
 
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Synrgy87

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Decided to go with one of these as I got fed up with the L50 flashing light thing happened way too often so as nice as that amp is when it's working it's been retired for now.

Got the H0100 in today first impressions were good running via RCA currently as i'm waiting on some cables to go from TRS to XLR from my E50 dac, at medium gain and low gain all is well up to max volume, high gain is good up until around 2 o'clock on the volume pot, however after that significant noise is noticeable (testing using my goto HD565 both balanced and unbalanced connection) While i wouldn't normally listen at this level it's not a thing that was present on the L50, thought i'd play around with the cables and find out where it was coming from.

Checked the RCA cables, checked the power cord, no difference, disconnected other devices sharing the same power strip/wall outlet, no change, seemingly stronger noise on one channel when disconnecting them individually, so tried to rule out the E50's RCA output, disconnected and the noise was gone, move to my backup DAC/AMP (FX Audio DAC X-6 with upgraded op amp) noise slightly different but it was back, Struck by the "DERP" lightening bolt from the old gods and another one from the new, "oh yeah the dacs are both connected via USB...) one overpriced USB cable with a ferrite bead added and one topping branded that came with the a topping DAC, disconnected the USB cables and switched over to optical noise is gone, switching to optical didn't remove the noise while the USB cables were still connected.

Guessing the SMSL HO100 doesn't deal with that kind of noise as well as the L50 does, as a sanity check i'm going to swap back to the L50 and reconnect the USB cables(connected to a Desktop PC so the USB noise is understandable, although the same source as the optical signal). I do occasionally like to use IEMs so I'm guessing they'll likely be more sensitive to the noise than the HD565s and other larger headphones are so this may be more annoying than it first seems.

Edit: yeah L50 none at all.
 
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RemLezar

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Dec 24, 2019
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Decided to go with one of these as I got fed up with the L50 flashing light thing happened way too often so as nice as that amp is when it's working it's been retired for now.

Got the H0100 in today first impressions were good running via RCA currently as i'm waiting on some cables to go from TRS to XLR from my E50 dac, at medium gain and low gain all is well up to max volume, high gain is good up until around 2 o'clock on the volume pot, however after that significant noise is noticeable (testing using my goto HD565 both balanced and unbalanced connection) While i wouldn't normally listen at this level it's not a thing that was present on the L50, thought i'd play around with the cables and find out where it was coming from.

Checked the RCA cables, checked the power cord, no difference, disconnected other devices sharing the same power strip/wall outlet, no change, seemingly stronger noise on one channel when disconnecting them individually, so tried to rule out the E50's RCA output, disconnected and the noise was gone, move to my backup DAC/AMP (FX Audio DAC X-6 with upgraded op amp) noise slightly different but it was back, Struck by the "DERP" lightening bolt from the old gods and another one from the new, "oh yeah the dacs are both connected via USB...) one overpriced USB cable with a ferrite bead added and one topping branded that came with the a topping DAC, disconnected the USB cables and switched over to optical noise is gone, switching to optical didn't remove the noise while the USB cables were still connected.

Guessing the SMSL HO100 doesn't deal with that kind of noise as well as the L50 does, as a sanity check i'm going to swap back to the L50 and reconnect the USB cables(connected to a Desktop PC so the USB noise is understandable, although the same source as the optical signal). I do occasionally like to use IEMs so I'm guessing they'll likely be more sensitive to the noise than the HD565s and other larger headphones are so this may be more annoying than it first seems.

Edit: yeah L50 none at all.
I also recently got the HO100 and it introduced significant ground loop noise that was not present with my previous amp. I'm not an ASR engineer so the only difference I can make out is that my previous amp had a SMPS and the HO100 has a linear power supply. The noise, for me, was very apparent even on low gain with sensitive IEMs. Both were connected via USB.

I just switched to XLR inputs today and it made a significant difference. While not completely remedied, the noise is gone at normal listening levels and the output of the amp has increased. Again, with sensitive IEMs, if I go passed 60% on medium gain and do something resource intensive on my PC it can transmit noise. I would never listen to anything at those levels though; going passed 60% on LOW gain starts to get unbearable.

So, for the most part, XLR is an effective band-aid solution. I was hoping it would do more but I knew already that optical to the DAC would do what I want by isolating it from the PC. Unfortunately the Topping D10B that I got for the balanced connections does not have Toslink input. Another option to look into could be the Topping HS01; a USB galvanic isolator. In the end I decided to return the D10B and have ordered the SMSL DO100 for the option to use optical from my PC but I will be testing it with USB as well.

To be honest your noise doesn't sound as bad as I was experiencing so I think you will be pleased when you plug those XLR cables in.
 
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Synrgy87

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To be honest your noise doesn't sound as bad as I was experiencing so I think you will be pleased when you plug those XLR cables in.
Hopefully they'll help, If it connect the HO100 to the L50 via the L50's RCA pas-through it introduces the noise to the L50, May experiment with the grounding, Optical may be the only way to get rid of it completely though. I have been looking at optical USB cables but they're pricey and minimum i could find was 5meter, have not tried these with USB DACs before so not sure if it would cause any problems or significant latency / delay.
 

RemLezar

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Dec 24, 2019
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Hopefully they'll help, If it connect the HO100 to the L50 via the L50's RCA pas-through it introduces the noise to the L50, May experiment with the grounding, Optical may be the only way to get rid of it completely though. I have been looking at optical USB cables but they're pricey and minimum i could find was 5meter, have not tried these with USB DACs before so not sure if it would cause any problems or significant latency / delay.
Makes sense to me. Whatever the issue is with how the device is grounded would likely follow through an RCA connection. XLR will be better at rejecting this noise. If you must use USB I will suggest again the Topping HS01.

I don't know why the HO100 behaves this way. I have tried it connected to different power outlets but the source of the noise must be the USB ground.

I have considered removing the ground pin on the cable but I'm not sure if that would be dangerous or what the path to ground would be at that point.

The reason optical USB are long is because that is their intended use; they can carry a signal many times further than copper without degradation.
 
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Synrgy87

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Makes sense to me. Whatever the issue is with how the device is grounded would likely follow through an RCA connection. XLR will be better at rejecting this noise. If you must use USB I will suggest again the Topping HS01.

I don't know why the HO100 behaves this way. I have tried it connected to different power outlets but the source of the noise must be the USB ground.

I have considered removing the ground pin on the cable but I'm not sure if that would be dangerous or what the path to ground would be at that point.
Yeah the Power ground doesn't seem to have any impact on it, it's coming from the computer's USB connector through the DAC and along the RCA cables into the HO100 and out of the headphone jacks, now... One of my XLR cables i ordered arrived (other one apparently delayed til Saturday) So can only test one channel at a time currently, but with XLR it's cleared up completely on headphones, I've not tried IEMs yet but I'm thinking it'll be the same story there.

Have also ordered an optical USB cable to see how well that works with DACs, curiosity has gotten the better of me there, should also be here in a few days.
Still doesn't feel right spending £80/€94/$95 on a USB cable :oops: but if it at the very least makes the RCA jacks more useful on the HO100 then I'll be ok with that.
Next up is to try and lift the ground connection at one end of a set of RCA cables.

So yeah a set of £5-10 XLR cables are a good option if you're feeding it balanced, I'm using some STAGG branded cables, relatively cheaply available on amazon, have used them before the cable is nice and flexible and the connectors unscrew and disassemble easily.

TLDR if you're planning to use it with the XLRs you're good, if you're wanting to use the RCAs YMMV/Some Jankery may be needed with the cables/Grounding depending on your setup.

Edit: lifting the grounds at 1 end of the RCA cables didn't help(actually made things worse by introducing some different noise so yeah don't do that). Something I should have checked even with the RCAs disconnected there's still a ground connection between the devices RCA grounds, so that did absolutely nothing good, removed the ground(earth) from the power plug and that's removed the PC noise(probably the first thing i should have done), so yeah ground loop caused by the USB and the internal PSU on the HO100, So when the optical USB cable arrives, and i reattach the ground/earth on the power cable that hopefully should be all ok. Hopefully my stupids can avoid some annoyance for others.

A revised HO100 with a ground lift switch might be nice as some other devices have.
 
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Graham849

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This suggests there is a rather 'quick acting' DC protection in the amp.

A potential benefit of the Pentaconn (aside from convenience) is that with low impedance headphones with long cables there is a chance stereo separation is technically better when a Pentaconn connector is used compared to a TRS jack (when it has a 3-wire connection).

Seems like a technically competent and affordable amp with both balanced and SE inputs. Balanced in could prevent ground loops as the safety ground may well be connected to the signal ground (needs confirmation of close to 0ohm between RCA shield and safety ground pin).
Where is this Pentaconn located, Amirm notes it as well in the OP?
 

staticV3

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Where is this Pentaconn located, Amirm notes it as well in the OP?
XQ2HO10031.jpg
 

Graham849

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Thank you I though it was a connector like xlr, just googled it. I have Motorola headphones with that plug
 

RemLezar

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removed the ground(earth) from the power plug and that's removed the PC noise(probably the first thing i should have done)
I figured as much. I would like to know if there's actually any danger to the amp by using it without the ground pin.

A revised HO100 with a ground lift switch might be nice as some other devices have.
I would prefer to just see a C7 connector like on the SMSL D-6.

I will be curious to hear how your experiment with optical USB turns out. I think they probably still use copper wire for 5v and ground so it might not work like you hope.
 

Lupin

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Tink they probably still use copper wire for 5v and ground so it might not work like you hope.
Ofc copper is used for the 5v line, you can't transfer electricity over optic fiber.
 

RemLezar

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Ofc copper is used for the 5v line, you can't transfer electricity over optic fiber.
Thank you for agreeing with me although I felt it was unnecessary to point that out.

I should say it depends on the cable whether it will actually supply 5v power at all. Not having power delivery would be preferable in this case, of course.
 

Synrgy87

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All of the cables have now arrived, late reply as I had a bit of a trip and fall so had some pain to deal with and work and sleep etc.

AOC USB cable did drop the noise a little but not much, possibly a slight change in the noise signature, the Power and Ground on this one are not galvanically isolated, which i expect, was more interested in whether there'd be any perceptible delays or issues with the DAC using the optical usb cable, but nope there wasn't it worked as expected, one thing is that with the AOC USB cable it does pick up some AC noise if near AC power cable, guess it's not very well shielded again why bother with shielding when the data is transferred via fibre optics(i've not opened the wire to have a look inside or slapped any ferrites/rings on it).

Next option is to look at some USB hubs, Optical is the real easy fix however optical has some drawbacks being only active while there's a signal meaning it switches on / off with a tiny audible pop, gets annoying when switching tracks / watching videos etc. Or... Cave in and go with something like the ifi defender or the ifi gnd defender. I could just leave the ground pin on the power plug disconnected but not sure how safe that is.

Has anyone seen what's inside the ifi GND Defender? wondering what it actually in the little box, bit pricey if all it does is lift the earth/GND anyway but i assume it's doing something more than that.
 

RemLezar

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AOC USB cable did drop the noise a little but not much, possibly a slight change in the noise signature, the Power and Ground on this one are not galvanically isolated
Yes, I wasn't sure what optical USB you went with but you would need to make sure they aren't delivering 5v power. I think Corning are what you want

http://archimago.blogspot.com/2015/05/measurements-corning-usb-3-optical.html

Or... Cave in and go with something like the ifi defender or the ifi gnd defender. I could just leave the ground pin on the power plug disconnected but not sure how safe that is.
but you should probably just forget about optical USB and go with the Topping HS01.

http://archimago.blogspot.com/2022/03/measurements-topping-hs01-usb-20.html
 
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kchap

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Yes, I wasn't sure what optical USB you went with but you would need to make sure they aren't delivering 5v power. I think Corning are what you want
I seems the Corning cable is made from Unobtainium. I'm sure another thread on ASR noted that the chipset that many optical usb3 converters used is no longer being manufactured.
 

AnalogSteph

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I could just leave the ground pin on the power plug disconnected but not sure how safe that is.
Cheater plugs are also used to break ground loops in audio systems.[5] This practice has been condemned as disregarding electrical safety.[5][6]

An unbalanced connection between two IEC Class I devices like a PC and the HO100 is doomed from the start. Under these conditions, use either galvanic isolation or a custom XLR adapter cable (signal --> hot, ground --> cold, ground --> shield, do not connect shield to XLR pin 1).
 
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