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MartinC

SMSL SU-8 Dac (direct to power amp)

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The search function suggests not, but does anyone here have any experience with the SMSL SU-8 Dac?

This is it:

https://www.amazon.co.uk/Decoder-2ES9038Q2M-768kHz-DSD512-Balance/dp/B07DQDNF6S

I'm wading through the threads on Audio Science Review* that got me interested in it, with me particularly considering it due to the balanced outputs that I could connect directly to my power amp. This would however mean I'd be relying on the DAC to adjust volume in the digital domain - something I've intrinsically always been against/avoided but I'm wondering if the 32-bit implementation makes it good enough to consider, at least vs the potential upsides of avoiding my current (unbalanced) pre-amp.

Given the relatively low price (£190) I'm currently quite tempted to buy one to try, thinking I could probably sell it on for not too much of a loss if it didn't work out.

 

*https://www.audiosciencereview.com/forum/index.php?threads/smsl-su-8-version-2-balanced-dac.5433/ for the latest version I'd buy, and

 https://www.audiosciencereview.com/forum/index.php?threads/review-and-measurements-of-smsl-su-8-dac.3778/

Edited by MartinC

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Super Wammer

Looking at the remote it has control buttons for volume so this would seem to suggest that the unit could be used straight in to a power amplifier and then control the level . While I have no direct experience with this unit I have used a MiniDSP DDRC 24 in my system and the sound quality improved quite a bit by using a digital signal direct in to this and htne straight to the power amplifier (unbalanced) . As when this unit was tested it did not measure that well and was noted as being noisy on the same site as your DAC was tested I can only presume the improvemnet is due to the much shorter signal path and the removal of a Pre Amp and DAC . Given this I would suspect that you might well find the same improvement in using a shorter signal path .

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5 hours ago, bencat said:

Looking at the remote it has control buttons for volume so this would seem to suggest that the unit could be used straight in to a power amplifier and then control the level .

Yes I know it's definitely possible. I'm more wondering if it would be a good idea :).

5 hours ago, bencat said:

While I have no direct experience with this unit I have used a MiniDSP DDRC 24 in my system and the sound quality improved quite a bit by using a digital signal direct in to this and htne straight to the power amplifier (unbalanced) . As when this unit was tested it did not measure that well and was noted as being noisy on the same site as your DAC was tested I can only presume the improvemnet is due to the much shorter signal path and the removal of a Pre Amp and DAC . Given this I would suspect that you might well find the same improvement in using a shorter signal path .

I have a miniDSP 2x4 HD actually, which I've been experimenting with correcting speaker response with but then fed through my pre-amp. I've never tried it direct as from what I'd read I really didn't think its 24 bit DAC would be up to the task of doing it well. Maybe I should try it out of curiosity though. I also have an older Tag McLaren DAC20 that I suspect is better than the miniDSP as a pure DAC.

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I use my SabreDAC straight into my power amp and bizarrely can control it with either a 36bit internal volume, a 24bit external volume, or a 64bit source volume. Since I can't tell the difference between them when playing music I use the 24bit control as this is easiest.

I absolutely cannot think why anyone believes a prehistoric carbon track and wiper contraption will attenuate an audio signal with less distortion and noise than will be accomplished in the digital domain (given sufficient processing headroom which is normal).

Honestly if that is holding you back just buy it. I'd be surprised if you go back in a hurry!

Be aware that you will play with volume much closer to 'full' than you are used to. As long as there is sufficient gain for your needs this is advantageous in terms of noise and resolution. If it is too quiet then you need the extra gain.

Some do prefer the sound of an active pre, I used to think I preferred the drive, but now think it was because of the differing volumes I was listening at.

Sent from my BLA-L09 using Tapatalk

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2 hours ago, Jazid said:

Be aware that you will play with volume much closer to 'full' than you are used to. As long as there is sufficient gain for your needs this is advantageous in terms of noise and resolution. If it is too quiet then you need the extra gain.

I hadn't realised that. I'll admit that I thought all pre-amps did these days for digital sources was just attenuate the signal. This is something I could get a feel for using my miniDSP, but if I go down the balanced route the gain of my power amp is then higher I believe, plus the output voltage of the DAC is higher (both presumably good things in this context).

Of course running close to full level is better in terms of the compromise of digital volume control.

Edited by MartinC

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Most modern dac/processors will have plenty of bits to throw away at the volume control, that will be the least of your issues. Worth remembering that, in a normal domestic setup with all the electronic equipment in the modern home, background noise will mean that many systems can barely resolve 16bits. Think about that.

The primary issue is matching gain throughout the system, in my experience this has a greater effect on the sound quality than any digital volume control.

Does your power amplifier have input attenuators/level controls? If so this should make gain matching quite straight forward.

Edited by MGTOW
edited for grammar
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11 hours ago, MGTOW said:

Does your power amplifier have input attenuators/level controls? If so this should make gain matching quite straight forward.

No. Well, other than the gain being 23dB in 4 channel mode vs 29dB in the 2 channel mode I use for my Bel Canto Evo 4 power amp.

Above I said the gain was different in balanced vs single ended mode but checking the manual I realise I was mixing it up with the 2/4 channel mode difference. The DAC I'm looking at has double the voltage output for balanced vs single ended though, which I'm guessing is probably standard.

Overall I'm assuming good 'gain matching' is basically a question of not needing to apply too much attenuation prior to the power amp? 

Historically I'd always thought a major concern with digital volume control was related to this actually, reducing SNR at source vs an analogue attenuation reducing both source signal and noise in a fixed ratio and so in principle preserving SNR. I realise though this logic only works if the noise/distortion introduced by the pre-amp is minimal, and that given how low the noise floor can be for good modern DACs the pre-amp may actually be more the limiting factor.

Edited by MartinC

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I've just had a very quick try with running my miniDSP direct into my power amp. I needed about 24 dB attenuation for a reasonable listening level, being fed into my power amp with its 29 dB gain. Which just goes to show how unnecessarily high the standard 2V DAC output level is. My speakers aren't atypically high sensitivity at nominally 88dB/2.83V/m.

It took a little while to swap over and back again, and wasn't properly level matched, but FWIW I think I preferred the sound via the pre-amp.

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Most systems have far too much gain, the more stages (components) in the setup the worse the problem. it helps a lot, in my experience, if you can balance the gain throughout the system in order to keep well clear of noise or overload.

if, as in your case, you can not control the sensitivity of your power amp then you have to use the volume control on the dac or preamp. Whilst not that critical with modern digital volume controls, it makes sense to use the least amount of attenuation you can, dacs that have several different output levels can help a lot but they are not common. More often than not amp with level controls are the usual solution, 'system' amps designed to work with a matching preamp can be awkward.

My own setup us set so that, with the digital output at full volume, the analogue attenuators on my power amps are set to a level just a fraction louder than I would normally use. They are then left at that level and the digital volume used normally, thus 'serious' listening is at close to maximum volume on the digital volume, I doubt if I 'throw away' more than a couple of bits (12dB of attenuation).

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FWIW I don't think having the gains of 23dB or 29 dB that my power amp has are particularly atypical. Google also suggests that 29dB is the THX standard apparently. I'll bet if most here tried a test like mine they'd have a similar finding.

It's not ideal, and DAC output levels are pretty standard, so basically it is what it is and the question to some extent remains whether digital or analogue pre-amp attenuation makes any more sense. I do have a couple of fixed attenuators somewhere (Rothwell or similar) but not sure if they offer any advantage when added to either of the above options.

@Millennium why your reaction to my post above?

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I agree, these levels are all pretty standard and it is far from ideal, if I had to run my power amps without attenuation, I would be in a similar situation. Having been around this particular hifi block a few times before, I was able to avoid this issue without much difficulty.

Loudness wars seen to affect CD players and dacs too, Red book standard is 2 volts out but many manufacturers go higher as in a direct comparison the slightly louder player will usually sound 'better', half a dB is not recognisable as a change in level but is enough to make a difference in comparisons.

If you can find your attenuators I would give them a go and see what happens, they would need to be -20dB to be really effective.

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40 minutes ago, MGTOW said:

Loudness wars seen to affect CD players and dacs too, Red book standard is 2 volts out but many manufacturers go higher as in a direct comparison the slightly louder player will usually sound 'better', half a dB is not recognisable as a change in level but is enough to make a difference in comparisons.

Yeah. Chord DACs have an output close to 3V I believe.

40 minutes ago, MGTOW said:

If you can find your attenuators I would give them a go and see what happens, they would need to be -20dB to be really effective.

I think mine attenuate less than that but -20dB ones are available, or indeed could be fairly easily made as they're just potential dividers formed by two resistors (although care would need to be taken re. channel matching). I'm not sure if there are any potential downsides to their use re. audio quality though? If not these may actually be more useful than I'd previously thought.

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