However, I've been craving lower latency. In order to achieve that, one must move up into the world of USB 3.0 interfaces (expensive), Firewire/Thunderbolt interfaces (very expensive), or professional audio PCIE cards (stupid expensive). Right now the USB 3.0 market is very small, and consists primarily of the Zoom UAC-2 for $300, and the Presonus Studio 192 Mobile at $500.
Recently the Presonus unit became available on eBay for less than $400. I picked one up for $380. Used ones are occasionally available for around $300.

After swapping out the venerable Behringer with the Presonus, all I can say is "WOW!" Zero, and I mean ZERO latency (<3mS) monitoring. That's even with the audio travelling first through Voicemeeter Banana, through the Reaper digital audio workstation (DAW) software, and back through Voicemeeter Banana (VMB). What a difference from the Behringer UMC202!
PowerSDR remains the usual stumbling block, as MON has many tens of milliseconds latency on it. But outside of PowerSDR latency is zero.
Leaving aside PowerSDR, the DAW is actually now the limiting factor. I need to find a better DAW! Windows and VMB will happily run at a Presonus buffer size of 32 (the minimum) at 96KHz. That's only 330 microseconds of buffer. Adding in the DAW I have to run at a buffer size of 128 at 96KHz. Of course that is only 1.33mS, but with the right DAW I should be able to get into the sub-millisecond range. BTW, same performance at 48KHz, just drop the buffers one increment and get the equivalent latencies.
Pro's: fantastic audio quality, really nice headphone amp (I need to get better headphones now!), effectively zero latency (outside of PowerSDR), highly flexible controls. It even has an external clock reference input!
Con's: highly flexible controls (it took me a couple of hours to unravel the mixer app that is part of the control panel), and cost. At the $380 I paid it's far cry from the Behringer at $60. Unfortunately it's a big cost leap to get into the zero latency interface regime.
As I mentioned, the controls are highly flexible, as it is designed for professional studio use. This may be too much complexity for some. Here's a shot of the Presonus control panel next to my normal DAW mixing board.

It all fits quite neatly underneath and between two of my monitors. I think I may move it over to the right side though.

73!
Scott