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USB bridge for old DAC1 or brand new DAC/amp stack?

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#1
Amir is amazing. This forum is fantastic. Discovered it a few weeks ago and my browsing history is 98.9% ASR now...

Context / history:

I have a Benchmark DAC1 (original, not USB) that I purchased used for $490 back in 2012. It is a 2003 build (!). It's been back to Syracuse once already for a pot replacement due to scratchy/balance issues. The issue comes and goes, but I know how to work the volume knob now to avoid the issues.

I primarily use it to drive my HD650 also purchased in 2012. Started driving the headphones via rear XLR outputs (-20db pad) using a cable I built myself (Neutrik XLR + Mogami W3106 dual-channel + Cardas connectors) and I'm really enjoying the sound.

I'm currently feeding the DAC1 with optical S/PDIF from a 2015 MBP, the last of its kind. I'm planning to get a new MBA/MBP this year, which will force me to go USB DAC.

Primarily ALAC (16-bit/44.1kHz) for my old music collection and Apple Music for the new stuff (and TIDAl HiFi when the $1.99 promotions are available).

I've been toying with a several options:
  1. Buy a USB bridge, like this XU208-based one for $40 https://www.amazon.com/Douk-Audio-Converter-Interface-PCM192Khz/dp/B085XPRSGM/ . My understanding is it will be essentially transparent for my use case. Thought about going with a Topping D10s as it measures very well and also has a DAC, but that increases my cost to $100. I also started to worry that the DAC in the D10s would obsolete my DAC1 with it's nearly two decade-old design. Has DAC technology really advanced so much as to make a $100 USB-powered DAC better than my DAC1? I know the D10s doesn't have a headphone amp, but that brings me to my next option...
  2. If I will get better performance out of a D10s, then maybe just get that as a stop-gap with the DAC1, and get a JDS Atom / L30 / A50s in the future? Also toying with the idea of building a Bottlehead Crack, which I know is a complete opposite direction of "reference" but I hear it sounds magical. Might just get both in time... ;)
  3. Just go all out and purchase a new combo DAC+headphone amp or stack, such as JDS Labs Atom stack or even a Topping E30/L30 stack.
So really, how obsolete is my DAC1 now? If the Douk Audio U2 USB bridge + DAC1 will do a good-enough job, I will likely just stick with that as it's only $40. If I can get significantly more performance (more than just objective measurements) with a $100-200 DAC + $100-200 amp, then it might make sense to just sell the DAC1 and start from scratch with a more modern setup.

The DAC1 has some sort of (unreasonable) sentimental value to me, and it's so bittersweet that state-of-the-art is progressing so quickly and at insanely affordable prices too!

I don't currently have any plans (yet) to get better headphones, as I am very happy with the current setup and I have still tons of potential with amplification. If I stick with the DAC1, I will likely still get a Crack and/or SS amp in the future. You don't miss what you don't know, am I right?

Sorry for the rambling; 'm overanalyzing again. The "correct" path forward and total cost keep creeping up as far as the A90 / D90 stack (LOL) then crashing back down to just the USB bridge for $40 when I talk some sense into myself. Rinse. Repeat.
 

AnalogSteph

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#2
Started driving the headphones via rear XLR outputs (-20db pad) using a cable I built myself (Neutrik XLR + Mogami W3106 dual-channel + Cardas connectors) and I'm really enjoying the sound.
A rather convoluted way of adding 60 ohms of output impedance and a tiny bit of low end if I dare say so.

So really, how obsolete is my DAC1 now?
Somewhat. Purely in terms of converter performance, a $200-ish MOTU M4 is arguably at least as good or better (the D10s is in the same ballpark with lower distortion), but the Benchmark still is no slouch and does better everywhere else - flexible analog output level handling so that 0 dBFS output level can be set from -1 dBu to +29 dBu in 10 dB steps and output noise can be reduced to -105 dBu(A) at least, and a headphone output that'll deliver +21 dBu into 60 ohms (that's no less than 1.26 W if you do the math, so if you ever decide to get into planars you'd be set). It's those things that distinguish a pro-level product.

Effective total dynamic range coverage for the line-out is 114-116 dB(A) instantaneous out of something like 134 dB(A) global with all adjustments taken into account. You want something like 110 dB instantaneous in real life for transparency under all circumstances, and it still passes that. Likewise, THD+N at -105 dBr @ 0 dBFS and even better at lower levels still qualifies as safely inaudible.

Maximum samplerate on the Toslink input on this older sample may still be limited to 108 kHz (96 in practice), but that's not a severe limitation either and easily accommodated by resampling if need be (the amount of material recorded at >96 kHz is likely to be quite limited anyway, not to mention our hearing does not care one way or another). Latency on e.g. a DAC3 HGC would be improved but (a) we're talking <1 ms and (b) purely for playback purposes you don't care anyway, this is merely a concern for recording setups.

The DAC1 includes an ASRC (AD1896) to incorporate its jitter rejection, and while newer Benchmark products pride themselves on 3.5 dB of extra headroom for intersample-overs, the DAC1 does not incorporate this yet and 2-3 dB of digital attenuation for "hot" material is advisable. Playback level equalizers (ReplayGain, SoundCheck etc.) often take care of that already. Arguably more problematic is the passband ripple spec of +/- 0.016 dB in what seems to be all FIR filtering. This may give rise to filter pre-ringing to a degree that Julian Dunn (R.I.P.) would not be amused by. Still no worse than the TI/BB PCM510x series DACs commonly used in AV receivers, mind you.

The ASRC filter passband ripple honestly is the only thing I'd potentially be concerned about. Otherwise, while the DAC1 may be measurably outdated in its class, it would remain perfectly serviceable.

The fact that it's on its second level pot and still has issues does not sound very confidence-inspiring to me though. While the symptoms do sound very much like a bad pot (which is odd, considering I'd expect a product like this to use nothing less than a premium part - if it doesn't, you may be able to get a bit of Deoxit inside though), I wouldn't rule out a hairline crack in the circuit board altogether.

Overall, I dunno. The DAC1 seems rather underused in your application. What you really need right now honestly is no more than a Topping DX3 Pro or something (or D10s/E30 + L30 or JDS Labs Atom). Driving HD650s isn't actually that hard.
 
OP
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@AnalogSteph, thanks so much for the detailed response.

Regarding the XLR output, driving the HD650 in balanced mode doubles the voltage (Pin2+Pin3 w/ Pin1 going to shield only). I can tell huge difference in dynamic range and clarity, and I'm pretty sure it's not placebo, but who knows... I've also read that it's not just the output impedance (the built-in HPA2 1/4" should be close to zero) but that Benchmark gave more care to the XLR circuitry as its focus is pro-gear.

Regarding the pot, it seems like it's a known design flaw that they fixed in later revisions with reduced DC offsets prior to the pot, but my unit isn't able to be retrofitted, so they just replace with the same pot, which will invariably go bad again. This info is direct from Benchmark.

As I'm very happy with the DAC1, sounds like the best path forward is to just get a D10s to use as a USB bridge, with flexibility to use it as a primary DAC in the future with an amp or in other applications or systems.
 

Tortie

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#4
@remlemasi

So did you buy yourself up a D10s and if so how you liking it as a spdif bridge?

Regarding the Douk Xmos bridge. I've been warned off about this brand years ago when they started making Beyerdynamic amplifier clones and selling them on eBay. The amps were garbage. Turns out their little USB bridge is no different. One YouTuber bought one and tested it with his linux setup. He went through two units. The first was defective. A replacement was sent which also had quality control issues.

 
OP
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Thread Starter #5
@remlemasi

So did you buy yourself up a D10s and if so how you liking it as a spdif bridge?

Regarding the Douk Xmos bridge. I've been warned off about this brand years ago when they started making Beyerdynamic amplifier clones and selling them on eBay. The amps were garbage. Turns out their little USB bridge is no different. One YouTuber bought one and tested it with his linux setup. He went through two units. The first was defective. A replacement was sent which also had quality control issues.

Not yet. I’ll probably end up getting it when I get the new 14” MBP, whenever that comes out.

Good to know regarding Douk. Thanks for the heads up.
 
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#6
I'm not sure if this helps, but I saw a cheap USB dongle on Aliexpress that outputs digital audio via an optical jack.

You could use this to feed the SPDIF of your DAC1?

I don't remember the brand, but it's a USB-A dongle that comes in silver, red or blue (and no, not a dragonfly). I think it was about $30. I wish I could find it again...
 
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#9
It's often a gamble yes, although some reputable brands do sell directly on Aliexpress too (I've recently bough a DAC from Hidizs on AE for example).

When we are talking in the order of $15, OP may be inclined to roll the dice! Especially if he's only interested in the optical pass-thru (and not the DAC component of such a stick).
 

Tortie

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#10
It's often a gamble yes, although some reputable brands do sell directly on Aliexpress too (I've recently bough a DAC from Hidizs on AE for example).

When we are talking in the order of $15, OP may be inclined to roll the dice! Especially if he's only interested in the optical pass-thru (and not the DAC component of such a stick).
I just wouldn't do it because such a device of poorly designed could introduce jitter. I remember Amir testing some of these Dac bridges and they added jitter spikes that weren't there in the original signal. If you buy this untested thing off AliExpress you have no idea if it's crapping up your downstream audio chain.

Why does OP need this device?
 
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#11
Why does OP need this device?
No one is saying anyone needs this. I was offering it as another potential way to add USB functionality to the existing DAC.

If these devices have been tested and have a poor track record, then fair enough. I have not owned one, so I can't comment on the quality of it.
 
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