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[J-a-k-e]

So I've finally decided that I should look at getting a decent multichannel audio interface. Something to replace the partially working solution I have which involves bridging a pci-e asus card and usb ODAC via asio so I can have an extra channel for subwoofer out (and after tweaking things still skip about every 10 mins when the devices fall out of sync). Does anyone know how the focusrite scarlett 6i6 compares with the ODAC in terms of audio output quality? The unit will primarily be used as an audio source/preamp poweramp to run floor-standing speakers and a passive sub.

[Matt]

I don't know about comparisons, but I'm using a Focusrite Scarlett 18i20 on my main system, and am totally happy with it.

[Hendrik]

I don't know about comparisons, but I'm using a Focusrite Scarlett 18i20 on my main system, and am totally happy with it.

I second that, got the same device at home.

[J-a-k-e]

Thanks guys, that's really great to know. I was somewhat on the fence however now I'm definitely saving to get the 6i6.

I tried telling myself that my xonar dx card is perfectly capable and if I think the ODAC sounds better it's all just a load of placebo. Unfortunately this is not the case, switching between the two leaves no doubt in my mind that the asus card just isn't up to standard quality wise.

[J-a-k-e]

So in the end I got the 2i4 after realizing that in the nature of recording interfaces the 6i6 doesn't output 6 analog audio channels as I assumed, & two of those channels are actually digital. So everything works fine & I've set the monitor output levels high so that I can control the volume via jriver. However the unit has an annoying dithering sounding hiss that sits at about 100dB below peak which sound like a low lever but it's clearly audible in a quiet environment standing about a meter away from my speakers. Do I have a defective interface? Or am I better off getting something like the Behringer FCA610.

[mwillems]

It's hard to answer without some info about your gain structure after the DAC.  The focusrite (if it's like it's bigger neighbors) puts out a "pro line-level" output which is about 10dB louder than a normal consumer line-level output.  That means it will play louder than a consumer DAC, but it also means the noisefloor will be higher than an equivalently rated consumer line-level DAC.  Depending on what kind of amp you have after the DAC, you may not actually want a pro-level line output (i.e. the amp may be designed to be fully driven by a  consumer line-level DAC). 

If that's the case you've got an easy solution:  an 6 or 10dB inline attenuator between the DAC and the amp.  It will push that hiss down significantly and will protect your amp from being driven into clipping by the super-"hot" output.  It should be sonically transparent (except for the attenuation).  That is to say it's a win-win; you're not actually giving up any volume, and you can attenuate the hiss.  Hendrik did something similar with his focusrite setup because his amps were designed for a consumer-level output (most are) .

All that said, depending on the gain of your amp, you may have a defective unit.  But it's hard to tell without knowing what kind of gain is being applied to the DACs noise floor and what the sensitivity of your speakers is (that can be a big issue).

FWIW, From what I've heard you'd likely have similar noise with the behringer.  If your amp has a high enough gain multiplier and your speakers are very sensitive, you won't be able to buy a low noise enough DAC to have no hiss without some attenuation between the DAC and the amp (ask me how I know).

[Zhillsguy]

Do I have a defective interface? Or am I better off getting something like the Behringer FCA610.

I tried the FCA1616 a few months back.... the first unit was defective, the second one was apparently OK, but I could not get consistent playback through the USB interface. It appears to me the Behringer ASIO driver was not fully developed or something...either way I sent it back. I really tried to get it to work, but between the inconsistent playback and LOUD pops when changing bit rates it was a no-go, totally unusable. I think the hardware was fine, it was clearly all software driver issues, worked similarly on my desktop (Win7 x64) and my laptop (Win7 x86). It seems there is a market niche to be filled with a simple multi-channel dac with balanced outputs reasonably priced, but maybe not. I have always questioned why many two channel devices work natively in Windows, but no multi-channel devices, they always require 3rd party drivers.

[J-a-k-e]

While the 2i4 has two balanced outputs, I'm actually using the unbalanced rca outputs to connect to two power amplifiers. A rotel RB-990bx running a passive sub, and a cheap rack mount with identical sounding gain to the rotel running a pair of floor standing speakers. Interestingly the focusrite sounds about 3db quieter than the odac at the same internal volume level in jriver. I couldn't find any specs stating the gain of the rotel but a stereophile review of a similar amp the RB-991 measured a gain of 31.8dB so I guess it's the same or close to it.

The floor standers don't have a listed spec for sensitivity, I believe they're about 86dB, definitely no higher than 90dB.

I connected several different audio devices and listened for the hiss (a highly scientific process which involves my running around disconnecting a lot of cables and placing my ear against a speaker) which was inaudible or near enough to it on an asus xonar dx card, an iaudio7 mp3 player and the odac Even the noise floor of the onboard realtek audio device was only half as loud as the focusrite.

[mwillems]

While the 2i4 has two balanced outputs, I'm actually using the unbalanced rca outputs to connect to two power amplifiers. A rotel RB-990bx running a passive sub, and a cheap rack mount with identical sounding gain to the rotel running a pair of floor standing speakers. Interestingly the focusrite sounds about 3db quieter than the odac at the same internal volume level in jriver. I couldn't find any specs stating the gain of the rotel but a stereophile review of a similar amp the RB-991 measured a gain of 31.8dB so I guess it's the same or close to it.

The floor standers don't have a listed spec for sensitivity, I believe they're about 86dB, definitely no higher than 90dB.

I connected several different audio devices and listened for the hiss (a highly scientific process which involves my running around disconnecting a lot of cables and placing my ear against a speaker) which was inaudible or near enough to it on an asus xonar dx card, an iaudio7 mp3 player and the odac Even the noise floor of the onboard realtek audio device was only half as loud as the focusrite.

I found the focusrite's specs, the unbalanced outs should be outputting a +5.5 dBU signal which is about 3dB quieter than the ODAC's peak output, so you have a very good ear  . It looks like the Rotel is fully driven around 2dBU, so you have about 3dB of "excess input" on the Focusrite that you could try trimming with an attenuator (i.e. inputs over 2dBu may drive amp into clipping).  But there's no reason that the unit (if functioning at it's rated electrical specs) should be giving that much noise compared to an asus dx or the ODAC

Before you send it back, I'd recommend trying it on some different USB ports; that recently cleared up a problem another user was having with his ODAC, oddly enough.  Specifically, if it's on a USB 3 port, try plugging it in to a USB 2 port, or try plugging it into a powered USB hub.  USB 3 ports give off some impressive interference; admittedly its in a band that shouldn't affect audio performance, but more than one forum user has had an issue that was resolved by changing USB ports, or moving a device to a hub.  

I used to be pretty skeptical that changing USB ports could make a difference, until I read intel's white paper on USB 3 interference, and experienced it myself with a few devices (some audio, some not).

[J-a-k-e]

I see what you're saying about different usb ports, this was definitely on my list of things I tried as I went through my testing process. I had a similar experience with the odac with my old am2+ motherboard although the hiss was still considerably less than I'm getting with the focusrite. When I upgraded to my current i7 ivy bride board the hiss of the odac dropped by at least 30db, scarcely audible over the amplifier's own internal circuitry. So I can see how a clean stable voltage can make a difference.

Also I discovered that connecting left and right audio channels from two different audio interfaces to the same amplifier, in my case the odac and the focusrite makes for some really weird interference and cancellation effects. I imagine this has something to do with the fact that many amplifiers share a common ground between the rca connections and speaker outputs.

Anyways, I'm going to see if I can test and compare my focusrite with another stock model in store, I'm hoping that mine is just a faulty unit.

[mwillems]

Also I discovered that connecting left and right audio channels from two different audio interfaces to the same amplifier, in my case the odac and the focusrite makes for some really weird interference and cancellation effects. I imagine this has something to do with the fact that many amplifiers share a common ground between the rca connections and speaker outputs.

Usually a grounding problem presents as hum not static, but I've seen static too.  Have you tried a balanced connection to see if the problem goes away (or is that not an option)?  If so it's definitely a shared ground issue.

Anyways, I'm going to see if I can test and compare my focusrite with another stock model in store, I'm hoping that mine is just a faulty unit.

That's a good idea, good luck!

[J-a-k-e]

So to cut a long story short, I ended up returning the focusrite and upgrading to the Behringer FCA610. Compared with the 2i4 the noise floor hasn't completely disappeared, it is however about 20dB lower. To the point that I can only just hear a hiss with my ear a foot from the speaker. so all in all I'm happy with the Behringer