Curiosity killed my cat when i saw the m500 available domestically (USA) on amazon prime with "free returns".
I will keep it for the month timeframe but I already know it's going back. It sounds **great** feeding my Hypex nc400 monoblocks, but it's like being sent a new racing red ferrari with a rev-limiter -- because at "maximum volume" (40) they basically reach "comfortable listening level" for working or concentrating with music on. If I really wanted to listen or just rock out, I could easily be listening at twice the actual volume. For comparison my old Topping DX7s would be at about -40 to -45 dB to achieve the same level as max volume on the M500 ; whereas "too loud" and "disturb the neighbors" levels could be reached with a normal "pop" recording at -25 to -20 dB. So in reality I'd like the XLR outputs feeding the nc400's to be at least 20dB hotter.
The weird thing is, the very first time I hooked it up to my computer (Atomic Pi running Lubuntu 19.04 with a custom KDE-styled and window-managed LxQt desktop) it achieved "normal" volume levels with non MQA files. Then I tried MQA on Tidal in Kodi (via Tidal2 plugin) and it got very quiet. I had to turn it up to 100% to achieve what i'd call a "quiet" listening level. Amazingly, as long I kept the kodi volume control at 100% the blue MQA decoding signal came on, displaying rates from 192k (John Coltrane "Blue World"), most displaying at 96k, and a few labelled as MQA still show 44.1k. The "quietness" didn't seem to be directly associated with MQA as the Kodi volume control (which i try not to use) reduced the volume linearly even though the display went back to normal PCM as soon as the kodi volume was reduced.
I never managed to get it back to the initial "loud" mode for normal non MQA files, even though I factory reset it several times and rebooted my linux machine for additional application of voodoo and cargocultism (when in doubt, reboot).
I also got it to completely puke and emit noise until I power cycled it trying to listen to some DSD demo music I have "ifi-micro-idac2-music-sampler"... Likewise, it pops and clicks through the speakers with totally indadequate or missing output muting relays. Switching inputs, or booting computer, causes clicks. Powering up from the front panel -- causes clicks and pops. POwering up from the back panel (as expected) a much bigger pop. No relays head cycling when power is applied so clearly there are no output protection relays to prevent pops during powerup. That's not acceptable in a $400 DAC.
Oh, and if you change inputs from the front panel, it'll continue displaying the previous input on the LCD (bug). Switching via remote displays proper input.
One thing I was worried about was the device having problems with mixed MQA and normal tidal playlists. I was worried it would go from normal loudness to very quiet on the MQA files. But in reality it goes into "quiet mode" and stays there -- maybe at best a -3 to -6 dB difference in MQA playback over normal. But nothing where it's at normal level (at 40/100% volume) and then suddenly blasting the full 300-400W per channel of my nc400's into my speakers rated at like 160Wpc. Which would suck.
Oh and compounding the issues -- the headphone ouput is absolutely too quiet for reasonable listening - at least into my easy-to-drive ATH MSR7's. Since I couldn't really get them loud enough to compare, i can't say whether the headpone amp is any good. Sounded clear at least.
This experiment answered one of my major questions about using Kodi and Tidal2 on Linux with MQA decoding. I figured it would need passthrough mode setup in Kodi and would only work in SPDIF. However that was not the case. Passthrough was not needed. Likewise I didn't even need to setup Kodi to access the M500 in SPDIF mode. Note that my setup, as is de-riguer for any Linux setup for serious audio, has no pulseaudio (biggest POS in all of linuxdom). Such output straight to ALSA allows my gstreamer-based Qt apps (see
http://trainspodder.com ) to do bitperfect audio on Linux even though thats not the goal of the app.
The experiment also semi-conformed that kodi with volume at 100% is "bit perfect enough" to allow the MQA stream to be recognized. Likewise I didn't need to worry about potential conversions that can be invoked in using the ALSA "Default" device as would occur with the following ~/.asoundrc setup:
I noticed no difference in the output stream or MQA decoding when switching between ALSA talking to SPDIF device versus default "analog" device using an alsa "plug" as intermediary to the audio device.
As to sound, it sounds better than my topping Dx7s, even if the M500 can't approach anywhere near the normal 4Vpp XLR output levels (which would translate to ear-blowing and speaker-blowing levels out my Hypex nc400's).
Compared to the dx7s, the bass is "stronger" -- not necessarily louder, but faster, and "thumpier" . Since that's one of the fortes of the nc400 especially combined with the Adantes.... you can really notice when you're being held back by your DAC or preamp. The M500 significantly lifts a veil off the sound, IMHO, compared to the dx7s. And that's even at low volume levels with the M500 at 100% volume.
Imaging seems better too, and there's a nice clarity to the high end that is not "etched" or bright, but rather "shiny" and "smooth". Feels natural, not fatiguing.
As is typical of SMSL, the build quality is inferior to the "feel" and solidity of the Topping DX7s. The control knob feels a little "wobbly" (not loose, but there's maybe a 1/2 to 1/4 mm of "play" that you can feel and makes it feel cheaper than it should be). But it really makes me wonder how many cycles of clicks it'll handle before wearing out.
This is the second piece of SMSL equipment (went through two pairs of A8's when they first came out before giving up on them due to concerns of longevity and display problems, as well as a feel of "skipping" registering movement on the volume knob) that had a faulty optical SPDIF "door". It basically stays open and stuck, and at the same time, the cable itself won't snap into place.
So even without the volume problem, it's going back (at the end of the month) due to the faulty optical SPDIF. And concerns that the volume knob will suffer the same fate as the A8's prior to its return. Of course, it has the same problem as Topping Dx7s with optical out on my samsung tv -- audio drops out regularly. (But works fine with optical SPDIF input on my Terratec DMX6fire card with my "Mudita24" control app for the card).
Overall I didn't like the physical features of the M500 even before ordering. I don't need optical inputs, and I certainly don't need two. I could have used an additional coax, or even better AES/EBU input - which I like to feed via a 75-110 ohm transformer to further isolates my noisy desktop from the DAC. Well I won't need to worry about that w/ the M500 because I'll be forced to manually plug SPDIF cables on the single SPDIF input. Sucks.
Likewise I don't like the odd shape. I much prefer the flatter shape of the Topping DX7S D70s, etc.
I'm hoping the D70 bluetooth version goes on prime with free returns because that'll allow me to evaluate the two DAC's side-by-side.
I'm wondering if the D70 has (as has been complained here) weaker bass compared to the M500. Might be same thing going on with the DX7s in comparison -- basically it's the sound of "output coupling capacitors" or the slew rate of the output op-amps, or the use of too-large series resistors driving the XLR output to prevent line-ringing problems typical of op-amps driving capacitive loads (e.g. audio cable). Conservative output designers like seeing clean signals on their scopes for ringing that can't be heard, but it significantly affects slew rate and "thumpiness" of the bass.
When are they going to make a DC-coupled audiophile DAC -- you know, like musicians get so they can also do "control voltages" to the modular synths or light controllers. And so that we can get a proper and not phase-damaged "thump" aligned across the frequencies from our loudspeakers. For example Presonus' Quantum and Studio lines feature "DC coupled line outputs"
https://www.presonus.com/products/Studio-1810c
Anyways, that's my review after 6 hrs of ownership and listening.
-- Niels