JohnEgan
Any advice or comments on similar experiences that may help would be appreciated?

 
The great thing about TB (besides it's huge bandwidth, bi-directional capabilities, daisy-chaining, plug & play, etc...)
is the ability to use various drivers over TB (FW, PCIe, Display-port, etc). In most cases, PCIe audio drivers will get you better performance than FW or USB (lower crackle free RTL's under heavy load, no added buffers, lower system overhead, etc..) on virtually any Mac or PC out of the box.
 
It does not end there, as you can add additonal drivers/features to the TB pipeline as needs arise. For instance, UA added it's "Star Clocking" protocol running over TB to their latest 2nd Gen Apollo's. No need for additional cables or spdif/word clock ports. One single cable daisy chained to each UAD TB device (total of 6 and up to 4 Apollo's) that carry separate DSP, audio & clocking streams. Want to add dual 4k monitors,  no problem, just daisy chain to the TB ports. I see lot's of possibilities for future audio/video products that we have not even begun to fathom yet as TB continues to mature (curently moving to TB3 and USB-C connectors). Future computers will have a universal port and cable system for all external devices. The type of device that you connect (USB, TB, Display Port, etc.) will determine it's speed and capabilities. What could be simpler.............this ease of use has been long over due in the computer industry that has had far too many types of chipsets, ports, adapters and cables to keep up with. One port type....one cable for all! Simplicity! 
 
Cheers,
 
Billy Buck
 

Jim Roseberry
Several things:

• Many USB2 audio interfaces don't cope well when connected to a USB3 port (especially 3rd party USB3 controllers).  Prior to Z and X series motherboards (and derivatives), literally all USB3 ports were provided by 3rd party controllers (as USB3 had not yet been integrated into the chipset).  Make sure the UFX is connected to an Intel USB2 port.
• Make sure the UFX is not sharing a root-hub with another device (especially not another higher bandwidth device).
• Using a USB hub for low bandwidth peripherals (dongles, keyboard/mouse, etc) can help free up USB ports (and makes it easier to avoid another device sharing a root-hub with the UFX.

Have no doubt that the RME Fireface UFX is an excellent unit (assuming it's in proper working order).
You should not expect glitches/etc when connected to USB2.
With a well configured recent make machine... you should be able to run substantial loads glitch-free at 48-64 sample ASIO buffer size (44.1k).
 

Jim - Good to see your well-informed opinions on this. But aside from a USB2 device's ability to manage bandwidth, do you have an opinion/recommendation on a <$400 device with a low enough round trip latency to permit a guitarist (like me) to record tracks one at a time, monitoring through an amp sim? I'm using an old M-Audio PCI card that is probably going to be obsolete under Windows 10. I have no first hand experience with USB interfaces, so have no idea if any of them are "fast" enough. I know I could monitor the interface directly, but I need the amp sim. Thoughts?

Thanks Jim and others, 
I've tried theses things and more, like disabling anything Im not using on PCI bus, except usually I record at 96K, PC probably does need upgrade now, albeit all worked pretty well with the PCI interface card (if that dates my PC), and its a random annoyance. I don't really doubt RME-UFX, but reassurances are good to hear. I'd had been holding out upgrading to get a PC and interface with TB2, but went with the UFX, and USB2 so shouldn't have had to upgrade PC yet. I guess the newer PC's mentioned will now have both options to use, albeit not of real bandwidth value to smaller scale applications, (or to me now), although a lot of newer audio interfaces are now using TB2 I/O's.
Anyway, thanks for the tips, Ill try a few more things suggested, and see how the Firewire works for me.
Cheers         

I can use my RME UFX on PC and Mac with round trip latency of approx. 9 milliseconds while input monitoring 10 tracks without issues so long as I don't use latency-inducing plugins. Whether I use a USB2 or 3 port or a TB2 to Firewire 400 adaptor makes no difference.

If I only need to input monitor 4 tracks that round trip latency can be dropped to 6ms at 44.1KHz.

RME's drivers are regarded as some of the very best there is. If you are getting crackles and dropouts I'd suggest looking elsewhere for the problem, such as plugins that use look-ahead creating latency or PCI bus Delayed Procedure Call issues on the PC itself. There's a useful free tool called latencymon that can flag up problems with dpc latency, which is typically caused by hardware drivers hogging the PC's attention for long enough to let the ASIO buffer empty.

As for Apple and TB, slow PC TB take-up has little to do with them any more than they can be blamed for Windows issues with Firewire. All current Macs have TB ports. An increasing number of PC motherboards and laptops are now appearing with TB as well, the issue is really one of Windows driver support.

Larry Jones
Jim - Good to see your well-informed opinions on this. But aside from a USB2 device's ability to manage bandwidth, do you have an opinion/recommendation on a <$400 device with a low enough round trip latency to permit a guitarist (like me) to record tracks one at a time, monitoring through an amp sim? I'm using an old M-Audio PCI card that is probably going to be obsolete under Windows 10. I have no first hand experience with USB interfaces, so have no idea if any of them are "fast" enough. I know I could monitor the interface directly, but I need the amp sim. Thoughts?

Presonus AudioBox VSL series yields 4.9ms total round-trip latency at a 64-sample ASIO buffer size (44.1k).
If you can up the budget to ~$650, the new MOTU Ultralite AVB yields 4.9ms total round-trip latency at those same settings... and has lower noise-floor(~-110dB).

Jim Roseberry
Presonus AudioBox VSL series yields 4.9ms total round-trip latency at a 64-sample ASIO buffer size (44.1k).
If you can up the budget to ~$650, the new MOTU Ultralite AVB yields 4.9ms total round-trip latency at those same settings... and has lower noise-floor(~-110dB).

Thanks, Jim! I'll take a hard look at both of those.

Larry Jones

Jim Roseberry
Presonus AudioBox VSL series yields 4.9ms total round-trip latency at a 64-sample ASIO buffer size (44.1k).
If you can up the budget to ~$650, the new MOTU Ultralite AVB yields 4.9ms total round-trip latency at those same settings... and has lower noise-floor(~-110dB).

Thanks, Jim! I'll take a hard look at both of those.

Avoid the PreSonus AudioBox VSL interfaces if you have an iLok. The VSL drivers will turn the iLok into an unrecognized, malfunctioning USB device. It took me 9 months to connect those 2 dots.
 
That said, the 44VSL I bought is a good piece of hardware. When I connected it as a class-compliant device to my Android tablet, Audio Evolution Mobile found and used it immediately. Easy peasy.
 
If you want to try a VSL i/f, try to acquire it from a place that will let you exchange/return it if you can't get the driver to play nice with your system.

Hmm wonder if you can efficiently connect FireWire devices to it via an adapter?

Guess this news delays my scheduled PC upgrade by 18 months.

TheMaartian
 
Avoid the PreSonus AudioBox VSL interfaces if you have an iLok. The VSL drivers will turn the iLok into an unrecognized, malfunctioning USB device. It took me 9 months to connect those 2 dots.
 
That said, the 44VSL I bought is a good piece of hardware. When I connected it as a class-compliant device to my Android tablet, Audio Evolution Mobile found and used it immediately. Easy peasy.
 
If you want to try a VSL i/f, try to acquire it from a place that will let you exchange/return it if you can't get the driver to play nice with your system.

I don't have any kind of dongle, so I might be OK with the 44VSL. I've never bought from Sweetwater, but it looks like they have a good return/exchange policy.
 
My real issue all along has been latency: Is the lag short enough that I'll be able to record a direct guitar while monitoring back through an amp sim in Sonar without committing the sim to my track? If I can't do that I will have to change the way I've been working for the past 15 years or so.

Larry Jones
 
If I can't do that I will have to change the way I've been working for the past 15 years or so.

I cannot resist temptation here... how did you adapt to the internet and cell phones?