Low latency audio interfaces for external effects?

Hello all,

I’m starting to realize I could really make good use of a multichannel audio interface (I’ve got a 2x4 right now that’s just really cramping my style), and in doing the planning/thinking I realized I could save some money on external effects if I could pass the signal into the interface, out through effects, and back in in a flexible manner with low-enough latency. This would also let me use digital/DAW effects in “live” contexts meaningfully. That’s a big enough improvement over my current situation to justify the cost of the box, since I could suddenly use my software effects to much greater usefulness and combine them with hardware effects rather than having both hardware and software versions of each for the different use cases.

(If it matters, I use Mac exclusively.)

That said, in my research I’ve come across basically three audio interfaces that are both in my price range and have provable real-world roundtrip latency low enough for my purposes:

  • The RME Fireface UC and UCX series - half-rack 8x8 analogue
  • The brand new Focusrite Clarett USB range
  • The Presonus Quantum fullsize version

For the cost, the Presonus offers the greatest on-paper value (Thunderbolt 2, tons of I/O, lower price, very modern architecture), but sacrifices the portability of the RME and Presonus’s build quality has always been - for me - questionable (I’ve owned several items of their older gear). I have a Scarlett now and it’s “meh”… adequate for what I used to do, but if I’m going to spend the money for another interface I’ll pony up the extra bucks for a better one. The latency is the biggest issue and there’s enough driver overhead to make it really frustrating - at 88.4 kHz / 64 sample buffer I get clicks and pops below 50% cpu utilization.

So, I guess my question is twofold: is the older Firewire RME stuff still the bee’s knees for DAW-based I/O ? Does the Presonus Quantum architecture improve on this significantly? And has Presonus’ quality gone up enough to justify it? All things being equal I’d rather have the RME, but if the Presonus (or anybody else’s stuff) is actually a true improvement I’d be willing to reconsider.

Any advice and other gear suggestions, of course, is welcome - these are the only interfaces I know of so if there are others in the same range - 8 true analogue in and out, sub-2ms proven roundtrip latency with Ableton, under $1600 USD, let me know!

I haven’t played with the Presonus or the Focusrite but I have the UCX and it is one of the best purchases I have ever made. I went through a number of portable interfaces before the UCX that let me down in live situations. I’ve used the RME almost everyday for the past three years and it hasn’t let me down.

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very happy with the UCX. it goes beyond being just an interface, and is easily the heart of a small-sized studio. very reliable, and pretty powerful.

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I’m using the RME very similar to what you want. In a live situation I use ableton live with the RME UC as freely programmable digital mixer controlled by the novation launch control xl.
I’m not using ableton other than just a mixer with tons of great fx.
I have the RME UFX in my studio which has the om board fx. The fx are not that great and I hardly use them. The compressors are nice but I hardly use them eather.
I would advise you to go for the RME UC. It’s a rock solid device that sounds great. Before the RME I was using a Motu 828 mkii and it’s like a blanket had lifted when I started using the RME.

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i’ve a motu ultralitle mk3 and for me is perfect, both latency and quality


The MOTU Ultralite mkIII has been a great audio / cv interface for many years for my needs.
Once, only once, I’ve had an issue with crackles during a show but I couldn’t tell if it was due to the interface, or OSX, or Live, or my settings, or something else. I restarted everything and it was all working perfectly again.

Ok, so those of you with the UC/UCX - the latency is low enough to go in, through effects in the DAW, and back out, in realtime performance situations? Do you think it’s performant enough to go in, out another port, through an external effect, back in, be mixed, and back out?

Hey MOTU fans, yeah, the ultralites were on my first draft of the list. I used to have an 828 original back in the day. But I haven’t seen real specs on the Ultralite series’ roundtrip latency / CPU utilization with Live. The RME converters are just 14 samples A/D delay till they hit the bus buffer and get DMA’d by firewire. Pretty much the same with Presonus (but only the Quantums), although they publish latency specs and not sample delay.

The main reason I took the MOTUs off the list is that they seem to require you to use the onboard mixer for lowest latency. That’s not acceptable to me - I want to mix in the DAW, with a variety of software and external hardware effects, so using a separate app/interface to do some of that mixing isn’t a solution. If that’s not the case, let me know!

For me it would be awesome to see real world cpu usage and latency in a 4 in, mix/send in DAW, 2 effects out, 2 effects back in (total of 6 in) and remixed in DAW, then out the mains.

Rather than making a new thread I’m bumping this with a semi-related question:

I’ve been recording all of my music without a computer and am looking into getting my first proper interface. I’ve tried to do some research but can’t quite figure out how reamping works… Would I be able to use the aforementioned Focusrite Clarett 4pre, for example, to reamp audio from my computer? Like, could I send a stereo signal from my computer out of line outputs 1&2, record the externally processed signal on line inputs 1&2, then use line outputs 3&4 to monitor the results?

Illustrating my thinking for reference:

Sure. This sort of processing is done all the time. As long as you’re not playing it back with a mix of the original signal (the latency won’t be compensated for so you get HF comb filtering or flanging) it’ll work perfectly fine. If the latency is too high you can either adjust the playback track latency to compensate or just resync the newly recorded effected track. You don’t need a clarett to do this, even a 2-in 4-out system can be wired up temporarily for this purpose, but if you have a rig you’ll be using frequently it would make sense to get an interface with enough ports to dedicate a few to this purpose.

Thanks for clearing that up for me!

Replying here again instead of making a new thread… After doing more research on which interface to get I seem to be hitting a wall. At a minimum I’m trying to have 4 audio ins, 4 audio outs, MIDI in/out and USB 3.0. The Clarett would be my bet but I’m not really sure I want to commit to using Thunderbolt (generally a PC user). Does anyone know of any comparable interfaces? The MOTU 624 also seems on point but even more spendy :disappointed:

Any reason you need USB3.0? USB2.0 should provide adequate latency for that channel configuration.

It’s not USB3.0, but I’m a fan of the Presonus cost/performance ratio (I have an Audiobox VSL that I’ve performed with which I like):

EDIT: to comment on durability, my 1818VSL has lived in a mobile rack for 6 years–on and off in a smoking studio and bumping around in my van for wilderness excursions