For anyone curious, the Quantum is performing extremely well (especially when it comes to round-trip latency).
With light projects, you can take the ASIO buffer size down to 16-samples... and playback is completely glitch-free.
That's sub 2ms total round-trip latency (exact figure depends on sample-rate).
 
When connected to Asus Thunderbolt-3 controllers, the Apple Thunderbolt-3>Thunderbolt-2 adapter works just fine.
Presonus recommends the Startech adapter... but the Apple adapter works just fine in this configuration.
The Apple adapter is ~$50.
 
The Quantum is a great performer, simple to use, and isn't overly expensive for the feature-set ($900).
IMO, This is by far the best audio interface Presonus has released.

Thanks Jim. So unless I misunderstand which is highly probable, I can purchase an ASUS equipped MOBO and the Apple connector, the Presonus Quantum and all should work well?
 
Are you getting this latency using the Z feature in SO? Or is this achievable in CbB as well?
 
 

Starise
Thanks Jim. So unless I misunderstand which is highly probable, I can purchase an ASUS equipped MOBO and the Apple connector, the Presonus Quantum and all should work well?

 
Yes, the combination works well.  
 

Starise
Are you getting this latency using the Z feature in SO? Or is this achievable in CbB as well?

This is monitoring via software... so you can achieve the same result in CbB (or any DAW application).
Actually... RTL at the 16-sample ASIO buffer size was closer to 1ms.
You can't run heavy loads at that size, but the fact that simple projects play glitch-free is great.
As machine speeds increase, you'll be able to run heavier loads at that 16-sample ASIO buffer size.

Thanks for this information.
 
I just wish Thunderbolt on the PC was more of a plug and play affair. We shouldn't need to buy a connector from Apple to make things work. It's a small nit I know.

Most Thunderbolt audio interfaces are Thunderbolt-2 (the exception being the newer UA Arrow)… thus the need for the adapter.
 
The newest Macs are also using Thunderbolt-3 (so you need an adapter with those as well).
 
UA offers a Thunderbolt-3 option for the Apollo series.  I believe it's $500 for the TB3 replacement card.  
 
Thunderbolt is now fairly mature on the PC side... and it's working well.
The cables/adapters are a bit pricey.  That's about the only downside.

Yes it's a minor nit and I'm sure others have probably made similar less expensive connectors work as well or this was my impression on the P site.
 
I think I'm beginning to let my guard down now with Thunderbolt. I was once very skeptical about the whole thing during that phase where things would only work with certain other things. I still doubt you can go out and buy just any Thunderbolt equipped MOBO and expect it to work. You mentioned Asus which has always been a staple in recommended MOBO hardware. Hopefully the market will sustain enough sales to make Future Thunderbolt implementation something that others will want to do.
 
I would  hesitate to recommend someone just go out and buy any Thunderbolt MOBO. I like to admire the testers from a distance.  Knowing Asus works well and at that performance level is a very attractive alternative to usb 2 or 3. Without guys like you trying this stuff out we wouldn't know, so thanks.

With Thunderbolt, it's important to know all the details *before* getting your audio interface.
ie:  Some folks think you can add a Thunderbolt-3 controller to any motherboard.  That's not the case.
The motherboard has to have a Thunderbolt-3 header... and specifically support Thunderbolt in the BIOS.
I also would avoid mixing brands.  If you've got a Gigabyte motherboard, don't buy the Asus TB3 add-in-card.
 
The Startech adapter that Presonus recommends is about $20 more than the Apple adapter.
It used to be closer to $90 (but has since come down).
 
I'm not a big Apple fan... but the Apple TB3>TB2 adapter has worked in every scenario we've tried (many different desktops and laptops).
 
 
 
 
 
 

Jim, thanks for that info on the Presonus. Timely for me.
 
I just purchased a silver face Apollo FW from a friend..had a Thunderbolt card in it so I thought it was a good chance to try jumping onboard the Thunderbolt direction. Turns out the Apollo via TB is totally unstable for me ( major dropouts in Cakewalk when instantiating VSTs and cycling through patches). UA tech support nicely told me they actually don't support CW and Studio One Pro so they've essentially sidestepped being of any help.
 
Loved the UA ecosystem, but it might be time to look into other options on Thunderbolt before totally ditching the idea. They essentially said it's a Cakewalk problem...but maybe it's really a UA problem.
 
I will look at the Quantum, being that it has good integration with Studio One. Your comments make me give that more serious thought.

FWIW, I believe the original (Silver) Apollo is actually running Firewire protocol over Thunderbolt.
IOW, It's not running "PCIe via Thunderbolt"... which is necessary for PCIe level performance.
 
I've got the Apollo-8 here... and it's just fine with CbB.
If you're after lowest possible round-trip latency, that's not the Apollo-8/16's forte'.
The onboard "Unison" processing is a great feature... but it comes at the expense of slightly higher RTL.
Of course, if you'll never monitor Native EFX via software, it's certainly worth the trade-off.
 
Using the Apollo-8 at 96k, the smallest ASIO buffer size is 64-samples.
Running moderate loads of native and UAD plugins, you have to raise the ASIO buffer size to 128 or 256 samples (to avoid pops/ticks).  Same project running with Quantum (set to 32-sample ASIO buffer size) is completely glitch-free.
 
If you want to do things like run Helix Native at higher sample-rates... with ~1ms total round-trip latency, Quantum is one of the best choices.  It's absolutely rock-solid.
The only downside to Quantum is that there's zero DSP for onboard hardware monitoring/routing.
It has to be done via software (you have to open your DAW application to route/monitor).
A workaround is to use something like the Presonus Monitor Station 2.
Say you've got a guitar processor like the Axe-FX or Helix Floor. 
You could connect the Axe/Helix to your audio interface via S/PDIF... and route the analog outputs to Monitor Station.
You could then play the Axe/Helix thru your monitor speakers... without having to fire up the DAW.
 
Presonus deserves serious kudos for Quantum.
By far the best audio interface they've released.
 

Jim, thanks a bunch for the info. 
I built this recent system with an eye toward moving from my trusted RME UCX to something Thunderbolt but obviously now I have to evaluate if the system is viable for that. I do have a friend dropping off an Apollo Twin tomorrow so I can test another unit that isn't "thunderbolt riding on FW". Might be a good bit of info to have.
 
All options are open now in my search :)
I noticed you guys do hourly consults. I might gather system info and enlist some help.
Brand new i78700 should be a pretty solid system and I thinking another set of eyes on the config could be $ well spent.
Thanks again for info thus far.