What is the Maximum Sample Rate Supported via USB Interface on a DAC?

Hi Sleepysurf - Thanks for the post. I should have clarified my answer a little better. Since your post I've rewritten it a little bit. the new format is working! Anyway, the Benchmark DAC itself can handle 24/192 but only up to 24/96 via its USB interface.

Hello Chris,<br />

There are DACS out there that are rated at the higher bit depth and sampling rates on other inputs, but on USB are limited to 16/44. These DACS would, if my understanding is correct, be a waste of money for someone who wants to download the 24/96 FLAC music files to take full advantage of their sound quality. When shopping for a DAC, one should read the specs carefully. There are a number of Firewire and USB pro-audio DACs out there that have 24/96 input, and will play 24/192 for under $500.00. A nice alternative to the Weiss Minerva for those of us who are lower on the food chain. <br />

<br />

Rob

Hi Rob - You make a great point. Readers need to be very careful when reading specs. Most USB DACs are limited to 16/44.1 or 48 via the USB interface, but support much higher sample rates via S/PDIF and AES/EBU. Some will also claim high resolution support but they only downsample everything above 16/44.1. I guess the moral of the story is to be careful and do some homework before making a purchase. We are all here to help.

What does, "without other common consumer interfaces" mean in your definition? For example, my EMU 0404 does 24/192 via USB and that is even using Foobar 2000 (a common consumer interface). Using the ASIO plug in, I was easily able to feed the EMU 24/176.4 and 24/192 material and the EMU would automatically "lock" on those sample rates when the material was played meaning that it was actually playing back those rates.<br />

Regards,<br />

Joel

Hi Joel - I was referring to hardware interfaces. Many pro devices don't have interfaces as simple as RCA outputs.

OK, got it. As for having simple inputs and outputs on the pro side, that's nothing an adapter or 3 can't fix!

First of all: great place here, thanks to Chris for making it happen! I'm an electronics engineer with a passion for great-sounding audio, and I'd like to shed some light on what the maximum sample rate via USB is.<br />

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Short answer: it depends. LOL<br />

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No, really. It depends on whether the USB port is a USB 1.1 or a USB 2.0 port.<br />

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USB 1.1 offers a RAW maximum bandwidth of 12 megabits/second. <br />

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Let's do some math (don't groan! LOL): <br />

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24 bits x 96000 samples/second x 2 channels = 4.608 megabits/second.<br />

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Looks like there's enough "head room" to go up to 192k. However, in practice, only around 40% of that RAW bandwith is available to data flowing through USB. (I won't bore you with details about overhead.)<br />

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That's why 24/96 has generally been considered the upper limit for audio over USB in the past.<br />

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Enter USB 2.0: RAW maximum bandwidth: 480 megabits/second. Oy! )<br />

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Even if we only figure 40% effective throughput (which is what throughput tests have confirmed over and over again), we still get around 190 megabits/second! That's almost enough for 14.2 channels x 32 bits x 384 ksamples/second...<br />

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I have one of those fine E-MU USB units (the Tracker Pre), and getting 24/192 material to its fine DACs is a walk in the park... SNR of those DACs (around 112 dB) ain't too shabby, either... connectors are gold-plated... and it's got a Class A headphone amp post DAC... my Sennheiser HD 280 Pro cans sound really nice over it. )<br />

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It's absolutely vital, however, to make sure that the USB port runs in 2.0 mode. So-called "USB hubs" (either external units, or built into keyboard or monitors etc.) can totally mess with things, and it's usually not a good idea to plug a USB 1.1 device into the USB port right next to where your USB audio device is plugged in, because the "weaker" (USB 1.1) device "pulls things down" to the lower USB 1.1 speed.<br />

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Hope this helps clarify things a bit.<br />

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If you got further questions... fire away!<br />

Hi TwoRocks - Welcome to Computer Audiophile. Thank you very much for the details!

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Can u give me some more update of this usb?<br />

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