Thoughts and recommendations for USB/thunderbolt interfaces and Apple Silicon Macs

I’m looking for some advice and thoughts on this:
Currently I use an Avid HDX card and an HD I/O with a Mac pro 5.1 cheese grater.
I only use the AES outputs, feeding my Cranesong HEDD for analogue loop plus my Avocet monitor controller.
This computer is 10 years old and getting long in the tooth.
Now that I am really getting comfortable and doing 99% of my sessions in Wavelab Pro, (and not really doing much in the way of mixing) I don’t need Avid’s top of the line DSP solution.
If I dump using a PCIe card, my computer options become much more open.
I’m anticipating a new mini Mac pro, and maybe a ‘pro’ Mac Mini this year./
Or i could buy one of the current 14" MacBook pros and use it in clamshell mode.
Or one of the M1 iMacs even

Obviously then I’m looking at USB or thunderbolt interfaces.
I need 8 AES I/O to fit my workflow. Any thoughts and suggestions?
I’m leaning towards the latest Metric Halo line, LIO-8/4p mkIV
Or actually Steinberg does the AXR4 which also has 8 x AES on the rear.
I guess the quality of the drivers and software are key to stability and usability.
Anyone have experience with either of these?

Any suggestions welcome.


I’ve heard good things about the Metric Halo stuff but haven’t tried it myself. I tried the MOTU 8D for my secondary machine where I needed AES and I do not recommend it. Very unstable and overall weird.

That experience led me to getting another RME AES HDSPe card.

Back when I moved from the old cheese grater Mac Pro to an iMac around 2013 I ended up getting a Sonnet Thunderbolt chassis to house my RME card (it needed two slots) and my UAD card.

It worked great and I could safely disconnect the fan for silent operation. Zero issues.

When I moved to the 2019 Mac Pro in 2019 or 2020, I was able to ditch the Sonnet Thunderbolt chassis because the new Mac Pros have PCIe slots again.

That being said, I still have a secondary rig and picked up a smaller OWC Thunderbolt chassis that houses just the RME card and again, with the fan safely disconnected for silent operation. It’s easy to do.

That’s a long way of saying that the RME AES card is SO stable, with really flexible routing via the Total Mix app which is fairly intuitive as far as interface mixer apps go, it would be hard to recommend anything else if you need that many AES ins/outs.

It worked so well I decided to get second one for my b rig so that all the I/O lined up when moving between machines.

I do have a 14" MacBook Pro but for that rig, I’m staying totally “in the box” and using Audeze headphones only, using the RME ADI-2 Pro FS R BE as the interface which aside from having a great sounding DAC and headphone amp, offers two different stereo monitoring paths which can be helpful for some situations.

Sorry for the long post but if I were in your scenario, I’d go with the RME AES card in a Thunderbolt chassis for the most transparent operation. Not sonically, but just operationally. No babysitting needed.

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Thanks Justin.
Yes, I too bought a MOTU 8D thinking it would be a backup / B room interface and I had the same experience as you. I was also wary as it has SRC by default on all I/O and wasn’t sure that was a good idea at all for my use case.

I have considered an RME AES card, but seems primitive and clunky, putting a PCIe card in a chassis. Also I tried that with my HDX card (which is a huge full size card) in the Sonnet chassis that can also fit a Mac mini, thinking I’d create a rack server DAW.
Didn’t work out well at all.
I’m sure the RME in a chassis is great, but somehow seems like holding onto old tech. How much longer do we think PCIe will stick around?

Food for though, anyways. Thanks for your input.


I hear you. I normally like to stay more on the progressive side of things but the RME PCIe card has improved my quality of life so much that I’ll probably use it until I no longer need more than one channel of AES in my life.

I just haven’t found anything more stable and responsive. The Metric Halo is interesting but has too much other stuff going on for my taste if all I need is AES and nothing else.

Also, the RME AES card can just be a single slot option if you only need half of the total AES I/O that it provides.

Stable and responsive is good.

Which Sonnet chassis do you have, and which OWC - do you think one is better than the other?
I’m thinking I could get by with the Echo Express SE I


I am normally a big OWC fan and grabbed the OWC Mercury Helios 3S for my B rig and it’s working fine, but for reasons I can’t really put into words, I tend to prefer Sonnet for the Thunderbolt Expansion PCI stuff. I feel like they test audio cards a little more thoroughly but I have no data to back that up with. Sonnet seems to specialize in these things a little more whereas OWC make a lot of different things.

I don’t think the Echo Express SE I was available yet when I needed one for my secondary setup so I went with the OWC.

Both allow you to disconnect the fan and neither have given me any troubles in the years I’ve been using them.

The nice thing about the RME card is that if you only need 4 stereo AES ins/out rather than 8, you can just use the main card that takes up one space. It’s the daughter card that provides 4 additional stereo AES in/outs that takes up the 2nd space.

The daughter card doesn’t even connect directly to your computer/chassis either. It just connects to the main card and sits in the space above it.

Well, things have moved on!
Loving the look of the new Apple Mac Studio.
Lots of power and connectivity. Not sure If I’m going to get a chassis for my HDX card as a stop gap measure, or sidestep to RME AES card or move on to something USB/Thunderbolt based.
Depends on supply issues with units like the Metric Halo mk IV Lio

The new Apple Studio display monitor looks nice too, but I like just a small screen in front of me - 24" max


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I’m interested in the new Apple Mac Studio line as well-it may be time for an update.

Peter, Justin, PG, anyone: what are your thoughts on configuration? Will the additional cores in the M1 Ultra processor be useful in the WaveLab mastering realm, or is the M1 Max more than sufficient for even the most elaborate montages with many plugins? Is there any benefit to be had by using internal SSD storage, instead of an external Thunderbolt array?

Thank you in advance for your opinions!

I don’t know if anything will change when WaveLab is M1 native, or any future changes to WaveLab but in the past, having less cores but more powerful cores was better than having a ton of less powerful/fast cores because only one core could really be used at a time for offline rendering or something to that effect.

I don’t know enough about the architecture to say if the M1 Ultra is worth it but my M1 Max laptop even with WaveLab running via Rosetta has been great. Excellent performance, and the laptop runs very cool and no fans ever kick on.

I’m curious to see how much better a native M1 version of WaveLab is.

Internal SSDs are just great. External Thunderbolt array might be good too, but everything “external” is a source of potential problems. I would not hesitate and use internal SSDs (NMVe)


[quote=“Justin_P, post:9, topic:766406”]
in the past, having less cores but more powerful cores was better than having a ton of less powerful/fast cores [/quote]

Correct today too. But if your main work is about batch processing, the more core, the better.

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So I ordered one.
Apple M1 Max with 10-core CPU, 24-core GPU, 16-core Neural Engine
64GB unified memory
1TB SSD storage
Of course that leads back to my original question re a new interface with 8 x AES i/o

Metric Halo unavailable
Steinberg AXR4 also unavailable, (could have been a good alternative)
Really hoped to avoid a PCIe chassis, but might be the only way.

PG: I notice when doing large batch processes that all the cores can be used, which is good.
I am very much looking forward to seeing how the new machine performs.
I would have bought the monitor too if they did a 24" version.
I like having just a small screen, low down infront, out of the way of my PMC MB2 monitors


I’ve had great luck using the internal SSD of my laptop and iMac Pro as my secondary machines, and I’ve had good luck using an OWC SSD in the PCIe slot of my Mac Pro.

I think at some point I probably had an external SSD over Thunderbolt 2 and that was OK too but the closer you stay to the processor, the faster things tend to be.

That said, I think for mastering work SSD over any modern port will not be a bottleneck for the audio aspect of it…but could be a factor when zipping larger folder and moving files around. Again, maybe only noticeable if you’re hyper-sensitive to how long things take.

So…I know that I probably sound anti-Mac a lot of places I discuss these things. That’s not true, but…there are some serious considerations about the new Macs.

The big one is that Apple’s NVMe is actually a little weird. Their controllers report a disk write as finished once it’s in the cache, rather than actually on disk. For a laptop, that’s not that big of a deal…it can keep power on until the cache flush is finished when shutting down normally or on external power loss. Every other new Mac really needs to run off a battery/UPS with a monitoring app that can shut down the computer safely without your intervention. This information comes mostly from people trying to port ARM Linux to apple silicon, which requires a much deeper look under the hood than what most people do.

They’re showing application and even system corruption from power loss technically during writes but after they’re reported as completed. It’s kind of scary. One example was from a power loss while saving a Garage Band project. GB knew it was supposed to re-open the project, but the project file was corrupt, so GB wouldn’t start again. It took a lot of dorky tech work to get it to open again, but the project couldn’t be recovered. And, apparently, the only way around it is to use slow drives that don’t have a cache (think USB thumb drives). For PG…it looks like flush() doesn’t actually guarantee disk writes, only cache writes. There’s a separate syscall for forcing disk writes, but doing so drops IOPS to more like hard drive values rather than SSD values or especially NVMe values.

It’s a really picky technical thing that seems to have been ported over from iOS, probably because they can always assume there’s a battery as well as particularly long shutdown process that the battery management can trigger if it needs to.

And, it’s possible that the first symptom of a problem would be your DAW just refusing to open, a project just not working, or the computer just not booting…and it theoretically could happen even if you do the normal thing of saving early and often just depending on the timings involved.

So…yeah…make sure you budget for a good UPS. You should probably do that anyway, but it’s an even bigger deal with modern Macs than modern PCs.

As for everything else…the processing and especially video seems like overkill for what I do. A normal Mini should actually be fine for me. But…I’m also fine on PC without the complexities/weirdness of pretty much having to rely on Thunderbolt…which is weird. Apples-to-apples, a comparably powerful PC is actually more expensive…but because I don’t own any Thunderbolt things, changing to Mac would be more expensive for me right now. The opposite may be true for people who’ve been on Mac (I haven’t owned one in a while).

Been running all my computers on UPS for many many years.
In a business environment you cannot afford to lose data or time.

Its a trade off: people want computers to be faster and writing large files or compressing large archives can be slow, so the OS and APFS tries to speed things up.
I doubt things are quite as sketchy as you say, but a UPS is good insurance anyway


Thank you all for your insights!

Just for my own clarity: as the M1 Max and M1 Ultra CPU cores both run at the same speed, is it safe to presume that even a complex montage with many plugins would not require more than eight performance cores (thus pointing to the M1 Max CPU)? Batch processing is a relatively minor part of my mastering workflow. Would there be any practical reason to need more than the eight performance cores of the Max (browser windows, email, billing software, printing, et al)?

They ARE that sketchy under the hood. But, the fact that people aren’t losing data left and right means that most people are doing what they need to avoid them, or at least that the problems don’t come up that often.

It’s not a fatal flaw…just something people need to be aware of.

And, yes, UPSs are somewhere between a good idea and necessary regardless. Other hardware vendors get almost the same speeds (or better if you go super high-end) without these problems. I think it’s a silly decision. But, it’s silly, not fatal.

Don’t think that power shortage can only harm Mac computers. Any computer can be harmed and you might lose data.
And even UPS are themselves not 100% reliable… not later than 3 hours ago, mine suddenly shutted the power and showed an unknown error. Apparently, the battery was dead.
I lost a small file in that process.

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Yes, it is.

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Yeah…I’ve had that happen.

Fortunately, the monitoring software alerted me that it was time to replace the batteries (or the whole UPS) before it became a problem.

I think it was around the 5-year mark.