SMSL SU-1 Stereo DAC Review

[Mark S.]

The question remains for me what perceptible loss is supposed to ever occur even without such kind of headrooms, considering that our ears' dynamic range goes down by definition as well, based on their steady noise- (or rather "tinnitus"-) floor anyway.

Also, even with 16 bit "only", the noise floor at about -93dBFS should be the only side-effect to be expected, given proper dithering and even 8 bit wouldn't be less "precise" in terms of analog waveform reconstruction, but only noisier.

BTW, the RU6 (you may or may not be aware) is a 'discrete resistor ladder' DAC and the precision of those resistors is questionable, in fact by Cayin's own admission it will add unacceptable distortion if you feed it a digitally attenuated signal (I'd guess a few dB would be OK, but not several MSB's worth).

 

[little-endian]

A lot of early CD releases are VERY 'quiet',

I'd call that "just right" with due respect to the dBFS scale back in the days. Against "quietness", there is a brilliant countermeasurement: turning up the gain.

10dB or more (in terms of RMS SPL's) lower than typical, compressed 'modern' ones

I'd call them "retarded ones", flavored with screaming irony where people jerk off to "high res", 24 bit and whatnot while in reality, probably 8 bit nowadays would more than suffice, given the lousy dynamic range which is left being used. Nowadays music landscape is overall pathetic in terms of quality with few exceptions.

even if they peak close to 0dB (many don't - go back far enough and you find discs that only hit -3dB or even lower), and you really wouldn't want to attenuate those in a 16-bit DSP, a lot of the music is already waaay down in the bottom 8 bits.

Maybe others can comment on that as I might be mistaken, but even with such DSPs, given ideal implementation, it should really "only" result in more noise but no other artifacts.

Not to say that it wouldn't be always nice to have more headroom and higher bit depths; at least, they don't hurt besides requiring more processing/storage capacities.

BTW, the RU6 (you may or may not be aware) is a 'discrete resistor ladder' DAC and the precision of those resistors is questionable ...

Guess that's partly why those are considered to be inferior to Delta Sigma ones against audiophile boutique affinities.

 

[Mark S.]

I largely stopped buying and listening to new releases c. 2003 (CD at the time) because I was so sick of the idiotic 'loudness'. Occasionally there'd be exceptions that didn't utterly suck, for e.g. Kings Of Leon's first album Youth And Young Manhood (although I wouldn't be surprised if it's since been brought "up to date" with a solid dollop of amping and hard limiting).

Whatever, I have 100's of GB of lossless rips going back ~20 years (many of releases that are now over 30 years old), the huge variation in the RMS loudness among them makes benign digital volume control (via a remote) for daily-driving a must, and doing it in 24 bits, out to a good 24 bit DAC is a must.

I am, BTW, well aware of how inferior the RU6 is to the SU-1 I'm waiting for - ** it's measured performance makes it almost unlistenable.

(** ETA >> I hope my sarcasm wasn't too subtle, or hurtful)

ETA 2 >> my intention is to use the SU-1 as my daily driver but occasionally the RU6 for more 'realistic', 'musical' 'organic' ear-bashing sessions, whether in-room or via Senn HD580's or modded Beyer DT 770 Pro 250's (moaaar bass!!).

 

[trungdtmc]

Does anyone have a picture of the inside of this DAC?

 

[Zek]

 

[trungdtmc]

Thanks. They don't even use an external I/V circuit, only use one lm47920 opamp ic for differential amplification

 

[TonyJZX]

is that bad? its $5 TI part

 

[Tangband]

is that bad? its $5 TI part

The parts inside this dac seems to be really good. In my opinion ( done some OP rolling ) theres no better sounding bipolar OP amp than LM47920 or lm4562. The mesurements by Amirm are flawless. If there is reliability problems it will show up soon.

This is a listening review with many other dacs :

 

[Fahzz]

I got an email this morning that the SU-1 DAC is on sale for $67.99 w/ free shipping on the Shenzen website if anyone is interested.

 

[Mark S.]

Been using the SU-1 for a few days now, having wrestled with EQ APO for the first two days (still not sure what got it working, tried everything and then suddenly there it was - maybe installing with elevated privileges).

So far so good, apart from the soft pop between format changes, changing media players or a few seconds after stopping playback.

I was using the RU6 exclusively for several weeks before that (listening a lot more than usual on account of the novelty of a new source) and something I noticed was that I frequently had 'phones on for a couple of hours or more at a time, at high volume while doing other stuff and never found it distracting, nor had the urge to turn the volume down or stop listening, so I guess it's safe to say that the RU6 is 'unfatiguing'.

However, this was exclusively in F2K via WASAPI, DAC in NOS mode (using EQ in F2K). The SU-1 is via DirectSound (as has always been the intention) with EQ APO, usually set to 32/176 but occasionally matching the sample-rate of the music (up to 192), I've yet to try it in F2K/WASAPI.

Haven't tried the USB isolator yet (I'm waiting for a USB 3.0 to USB 3.1 adapter), but the noise via the amp (speakers, not headphones, the latter has never been a problem) is considerably reduced from the (notionally crappy) Play!3. When I say "notionally crappy" I can say with some confidence that the SU-1 is a major step up - listening to some jazz trumpet (24/192) as I type and boy is it nice (for want of a better word).

 

[LtMandella]

I bought SU-1, I listen on m-audio bx5 3d monitors, my head and ears get tired quickly. I can not understand what is the reason, who faced?

your speakers are likely the problem. I listen to this dac with Ref3A Decapo I speakers using a Grounded Grid tube preamp and and A07 class di chip amp, the sound quality is superb. I can and do listen for hours with no listener fatigue.

 

[radix]

So far so good, apart from the soft pop between format changes, changing media players or a few seconds after stopping playback

Have others noticed the pop between format changes? I had that on a DX3Pro and ended up resampling everything to 24/48 (or something like that) to avoid format change pops.

I will be using this DAC between a raspberry PI and an unbal preamp, so it seemed like the right tool for the job. Have not received it yet, it's stuck in customs.

 

[LtMandella]

Never heard a pop from my SU1 in any situation including when changing inputs. I use it with both USB and Optical input. Have not tried the COAX input yet. I connect the SU1 to either a Grounded Grid tube preamp, or directly to an AIYIMA A07.

 

[Mark S.]

Have others noticed the pop between format changes? I had that on a DX3Pro and ended up resampling everything to 24/48 (or something like that) to avoid format change pops.

I will be using this DAC between a raspberry PI and an unbal preamp, so it seemed like the right tool for the job. Have not received it yet, it's stuck in customs.

I've heard a few mention it with this and others, IIRC it only happens with Windows. It does sound like something 'resetting' or connecting/disconnecting, but I get every time I stop playback (after about two three seconds) even when the bit-depth/sample-rate of the song last playing is the same as set in Windows Sound. Also when opening/closing any program that requires an audio device (players, web browsers, audio editors etc').

It's quiet enough that I only notice it through 'phones and I've already got used to it. Doesn't do it between songs even if the bit-depth/sample-rate changes from one to the next (which I might have implied it did in the post you're replying to). I installed the SMSL (XMOS) driver over the Windows one and it made no difference.

All that said, it does make me a little uneasy about the thoroughness of its engineering and long-term reliability. As I do with all low-power electronics I'll be keeping it powered on 24/365 (except for time away, obviously), I think it's easier on them over time than hundreds or even thousands of on/off cycles, and my experience over the last few decades has largely borne this out (**).

ETA >> Just listening again and it's actually two pops separated by about half a second, L channel then R. In Foobar (or any media player), always at the start of playback (but not between songs) and then about three seconds after stopping it (if you resume playback in that three seconds, no popping). Weird, frankly, never had any audio device behave like this before. The actual audio signal is muted for the duration of the double pop when starting playback, c.1 second, which I am now starting to find irritating.

ETA 2 >> (**) re. power cycling - assuming my unit isn't actually faulty, I'll be relieved if this only is a thing (problem?) in Windows, because otherwise it suggests something in the DAC being switched on and off by firmware, and over years that's going to be tens of thousands of times.

Could it be the unit going into some sort of standby mode? Would they be gormless enough to set that at three seconds?

 

[Mark S.]

Well, my OCD (or is it paranoia?) has well-and-truly kicked in and I'm now determined to get to the bottom of this. I'll be trying the SU-1 with my laptop and old PC (when I get it out of the wardrobe), which are both also windows 10. Also going to try the other inputs, from PC and bluray player.

ETA >> Just tried the PC's optical out - no popping, although a different, louder click when going from F2K to opening YT in a browser.

 

[Zek]

Could it be the unit going into some sort of standby mode?

Does this phenomenon have something to do with the setting of the USB DAC power supply, some kind of power saving mode or something similar.

 

[Mark S.]

Does this phenomenon have something to do with the setting of the USB DAC power supply, some kind of power saving mode or something similar.

I was thinking along those lines. If so, having it kick in after only three seconds of no audio signal would be, well, gormless.

 

[Mark S.]

This looks promising;

https://www.audiosciencereview.com/...os-driver-settings-for-no-cutoff-delay.25838/

To quote from the OP;

The default is "on when needed", however if you want no latency between start song/video - dac playing said sound - you need to set it to "Always On"

This is by no means maliciousness on behalf of DAC manufacturers (except the ones that hide it despite the above efforts), but complete and utter incompetence or at the very least ignorance.

I've found the XMOS driver control panel, will explore tomorrow (it's late and I'm tired).

 

[Shadow12347]

This looks promising;

https://www.audiosciencereview.com/...os-driver-settings-for-no-cutoff-delay.25838/

To quote from the OP;


I've found the XMOS driver control panel, will explore tomorrow (it's late and I'm tired).

Great find! As I mentioned a page or so back, we bought 4 of these for work, and I was having the same problem. I finally had time to work on setting everything up and I found it was happening on all of them.

I'm at work waiting on someone still, so I figured I'd try this out. For the driver from the SMSL site for the SU-1, the correct file is the one highlighted below:

After following the guide, I was able to set that option, and the problem is solved!

 

[Mark S.]

Great find! As I mentioned a page or so back, we bought 4 of these for work, and I was having the same problem. I finally had time to work on setting everything up and I found it was happening on all of them.

I'm at work waiting on someone still, so I figured I'd try this out. For the driver from the SMSL site for the SU-1, the correct file is the one highlighted below:

View attachment 292811

After following the guide, I was able to set that option, and the problem is solved!

View attachment 292812

Yay! It worked!

That 'sleep' setting is presumably a default intended for mobile devices (to save a watt, or fraction of) and it's pretty silly left set for a desk-top unit. I wonder how many returns SMSL and others have had to deal with thanks to this?

ETA>> - congrats on being able to fix four of the little beasties.