Alright, so I want to share my experience with the M500 thus far too.
I'm gonna take a few steps back and take you on my journey of annoyance, disappointment, debugging, pain and eventually joy.
If you want to read just the M500 stuff, skip to the last paragraph.
Being in great company of audio enthusiast in this forum I suppose that most of you like reading the various endeavors of others.
For over 4 years I had been a very satisfied owner of the SMSL Mini DAC SD-793II.
At the time of purchase, that little thing cost me around 55 EUR (approx $61 USD) but has gone up to almost 70 EUR (~ $78 USD) since my purchase.
It was my first "real" DAC with a builtin headphone amp and wow did that open my eyes. It's a very simple device with only 2 spdif inputs, one optical and one coax. The build quality is very nice, the buttons are snap-in toggles and will click audibly (like an mx-blue keyboard switch), one for power and one for input select.
The RCA out is fixed volume and the knob on the front is only for the headphone out.
The rest of my listening equipment is composed of a pair of KRK Rokit RP6 G3 and a Beyerdynamics DT990 Pro in the 250 Ohm edition.
Since these were active studio monitors and the little SMSL DAC had no volume control for the RCA, I searched around a bit, got myself a little DIY aluminum box, some cinch connector, good quality wire, good quality stereo analog potentiometer and built myself an RCA volume-control-box, sometimes also known as "passive preamp".
After about 2 years the KRKs started to make a buzzing noise when idle (mostly inaudible when playing music) and after some disassembly and testing around it was actually the transformer that was vibrating at the mains frequency (50Hz / 230VAC here in Germany).
These trafos were supposed to be decoupled from the chassis by a sheet of hard rubber. It seems that over time the remaining plasticiser had gone and essentially rendered that sheet to a mere piece of plastic, eliminating any decoupling effects.
With a bit of foam rubber and automobile-grade bodywork adhesive I was able to fully decouple the trafos from the chassis once again, making them completely inaudible due to a lack of any resonance body.
Fast forward another 2 years and my 1st gen AntLion ModMic died, right at supposed bend-protection at the mini-SMA? connector.
Since that thingy lasted over 5 years I couldn't really complain other than these mini-SMA connectors not being really available, which made reparing them rather infeasible.
This made me think about what I wanted to replace it with. I don't think I have to tell you how bad onboard Mic inputs on PC mainboards are, probably everyone had their fair share of GPU interference, white noise and all kinds of other disturbances.
So I went ahead, got myself a little Focusrite Scarlett Solo 2nd Gen together with a Marantz MPM-1000 to hopefully increase my voice quality quite considerably, making it much more enjoyable for all my friends with whom I regularly spent numerous hours in our teamspeak.
And it was a bliss, at least at first...
Almost every Windows upgrade gave me huge pain with the focusrite drivers and after a pc upgrade I started having USB interference issues, causing crackling and other nasty distortions in my captured signal. After my countless searches and google and product reviews of various Focusrite Scarlett products, this seems to be a common issue. This was just very recently confirmed yet again when I went through amir's review of another Focusrite Interface here.
I did my fair share of further searching for possible solutions, explored different ares of other audio devicing with respect to (studio) recording gear and considered the increasing clutter on my desk with multiple devices (DAC, passive-preamp, focusrite).
often incorrectly attributed to Einstein (exact origin unclear) said:
The definition of insanity is doing the same thing over and over again and expecting different results.
Well, here I am, most likely insane.
I bought a Focusrite Scarlett 6i6 2nd Gen. Yes, you read correctly, another Focusrite Scarlett with a USB connector.
The reasoning behind this went something like this:
I'm using a dual PC setup here at home, one machine is my workstation and daily driver running Linux, which has been my main operating system for well over 10 years now, I don't even know how I could be really productive on Windows anymore...
The other one is purposely setup for just gaming and only booted in the evening when I'm going to actually play games with some friends.
The features of the 6i6 led me to believe it could replace all 3 little boxes on my desk all at one.
It had separate volume knobs for headphone out and lineout (which turned out to be actually balanced TRS), a builtin DAC, a standalone power supply, making it usable without a usb connection and most importantly: it had an spdif input via a coax connector.
After having figured out all the hoops you have to jump through to get it actually working (i.e. setting the internal clock to the same sample rate on all devices interacting with that interface and configuring the flexible internal-routing inside that device like I wanted to) I was never really satisfied with it.
I have the strong suspicion that the DAC is not really great and that there is something really wrong with the internal clock generation because I had numerous blips in the audio output when feeding it over coax spdif alone.
And eventually... my friends in teamspeak reported that the weird crackling noises and distortions had re-appeared.
I'm unable to put my annoyance and anger into words. This was such a big kick in the nuts for going through all that trouble of re-organizing the whole setup in the hopes to eliminate all my issues at once.
What followed was a painful weekend of debugging, re-plugging, re-wiring and even freshly re-installing windows.
During this time I was really through and started to notice GPU interference in the line out and headphone out with actually *muted* windows audio when playing games. I was confused, surprised and, once again, annoyed. It didn't take long to figure out that it came from the USB connection.
I took different attempts at trying to fix it and eventually ended up building my own "ground-lift" usb cable by isolating the ground of the cable between my gaming rig and the focusrite.
However, that only fixed the interference on my output signal and didn't help with the crackling distortions of my recording signal whatsoever.
In the meantime I had sold my small SMSL DAC to help out a friend whose amplifier had just died and he was in need of some kind of replacement to at least have headphone audio back. As he was tight on money I sold it to him, leaving me with no option to turn back....
Having been through hell and back with that mess I took another gamble and replaced the mainboard and the power supply with even higher grade stuff, in the hopes to fix my usb issues.
I guess you can imagine what happened: Correct, it actually got way worse.
With the new mainboard the interferences with a "normal" cable were even louder than before, the crackling distortions in the recording signal did not improve and my "ground-lift" cable would actually make the focusrite disappear every 15-30 seconds of using it, requiring to powercycle the focusrite to make it usable again (for another 15-30 seconds).
At this point I was absolutely fed up and didn't even know which way to turn from here.
After spending some weeks of thinking on what I wanted to do, leaving my friends in teamspeak with some pain in their ears for all that time and saying "sorry" every once in a while I found myself here on Audio Science Review.
I guess this is the right time for saying a HUGE THANKS to amir and all the other people in this community for providing absolutely stunning measurements, reviews and help throughout the whole forum. I truely admire the work you do here.
Unfortunately I was in a rather volatile state, I just wanted to have "some audio" without issues and distortions.
Due to that, I was too quickly impressed by the review and measurements of the Topping DX3 Pro without spending proper attention to the last couple of pages in that thread and straight up ordered it on amazon.
Obviously my exemplar was of the infamous V2 generation and exhibiting *severe* issues with the digitally controlled volume knob.
It just went all over the place, no matter what I tried. Even careful and smooth turning in the same direction would make the volume jump up and down several steps. Slightly tapping on the volume knob would sometimes change the volume too and gently but quickly turning it *very* slightly left and right would make it go totally crazy.
That's very unfortunate because I immediately fell in love with the design and display, it was just so pleasing to look at. But for that price tag the completely broken volume knob was simply inacceptable so I had to return it.
I then spent about two weeks reading through different reviews and measurements, thought about the amount of money I was willing to invest and what compromises could be acceptable.
Eventually I ended up having to decide between the Sabaj D5, Topping DX7 Pro and the SMSL M500.
Quickly I ruled out the DX7 Pro in the fear of a broken volume knob again.
The decision between the D5 and M500 was considerably harder. I spent countless hours going over the measurements and conclusions of amir again and again and again.
As I only wanted something for 44.1kHz audio and not go into the ultra-high-samplerate or even MQA regions I assumed the reports of issues in this area with the M500 would not affect me, since I wasn't even going to connect it via USB.
When I stumbled upon some volume issues with the Sabaj D5 I became more and more hesitant towards it after being very disappointed and biased with my DX3 Pro experience.
The final decision towards the M500 was based on:
- slightly higher 300 Ohm headphone output power (63mW vs. 56mW)
- slightly less headphone output impedance (2 Ohm vs. 3 Ohm)
- having *two* optical inputs (both my PCs have optical outs, one of them always had a cheap little optical->coax converter attached to it)
- being 60 EUR (~ $67 USD) cheaper than the Sabaj D5
Now for the actual feedback regarding the M500:
It's a bliss. It's very much the same joy I once experienced with the entry-level SMSL DAC I purchased years ago.
The sound is crystal clear with quite noticeable more "oomph" and clarity in the lower frequencies, suprising me with what kind of punch my studio monitors could actually produce. The DAC and output section of the Focusrite Scarlett 6i6 is nowhere near the fidelity of the M500.
So far I've had zero issues with the device, even the digital volume control has not had a single hiccup yet.
The remote control is a great addition, making it much more comfortable to switch between inputs and outputs.
And this is also the one and only slight "meh" I have found so far: There is no way to disable inputs. It will always cycles through all of them (usb, opt1, opt2, coax).
This is where SMSL could come up with a feature in a future firmware upgrade, giving the user the ability to just disable certain inputs, making switching between the remaining inputs much quicker and less annoying. Especially for people like me, who are using more than one input this might prove beneficial and would be a welcome improvement.
Apart from that, I'm still a tiny bit worried with output power of the headphone output. When I'm using it only for listening to music and the volume settings in the music player and pc output are set to 100% it's all fine. But on the gaming rig with running teamspeak, some other stuff in the background I'm sitting at volume 20/40, sometimes going up to 25/40, leaving me to believe there might be a situation where I could use a bit more.
But so far that hasn't happened yet.
Since the recent posts have been about the reconstruction filters, I just want to share that I'm using the "Apodizing" one, which made the most sense to me in the measurement graph from amir.
Cheers and greetings from Germany
foxxx0
PS: Some of you might now ask "but what about the crackling distortions in your microphone signal". This has since been solved too. In my great despair I actually got myself one of those "iFi iDefender3.0" USB-jitterbug/ground-loop-isolators. Seeing that my Focusrite Scarlett 6i6 is not USB bus-powered but instead has its own power supply I thought this would be my last attempt before giving up on it. And what can I say: it worked! It actually worked. It seems there is some very bad noise and interference on the USB connectors on my gaming PC and simply isolating the focusrite from that made all the distortions disappear, finally! It was a pricey last-resort and while I don't expect it to improve the brilliance/resolution/quality of the my microphone signal (which won't happen as amir has proved already, if anything it is more likely to impact it negatively) it does exactly the one job I bought it for: getting rid of the ground-loop and other disturbance on the USB connection to the focusrite.