MOTU

I bought this card to use it with virtual instrument plug-ins of acoustic pianos, to have a better sound than with the headphone output of my latpop.
I also wanted MIDI to connect my digital piano to the soundcard.
I went for Motu due to their good reputation in terms of audio quality and I got the Audio-Express because I had no need of many audio inputs.

I use it with an Acer laptop running Windows 7 an I connect the card via Usb2.

UTILIZATION

No issues with the drivers, no crashes with USB with a laptop PC.

This card is not dangerous(!!): It hasn't harmed my speakers (due to a very high gain) because I have updated the firmware.

I haven't used the recording functions but, apparently, you can use all (6) inputs simultaneously.
As for the latency, I go down to 512 or 256 samples, depending on the virtual instrument plug-in (very resource-intensive piano banks). The latency of milliseconds depends on the frequency, I have gotten it down to 5ms at 96 khz.
I think it's possible to go even lower with sequencers/recorders (Live, Cubase, etc.)

GETTING STARTED

No installation problems, the manual is easy to understand.

I had an incompatibility issue connecting it via a firewire extension card connected into the expresscard port of my laptop with a Texas Instrument chipset. It would only work at 44.1khz via firewire.
However, I had no problems via USB with any resolution.

Firewire must work better on a Mac...

OVERALL OPINION

It's my first audio interface and I've had it for 2 years. The audio quality is good, the sound is clearly better than with the laptop's headphone output.

It can also be used as a small mixer without a computer, which comes in very handy when you want to use 2 powered speakers with 2 mics + 2 instruments (or 4 instruments) + a player via spdif. There's no need to carry with you a more bulky mixer. Even more so considering that the Motu is well-equipped: Balanced inputs/outputs + phantom power on the mic inputs, different mixes for PA and monitors.

If I had to replace this soundcard, I'd be loyal to Motu, but since I have gone back to hardware I don't need an audio interface.

I am using this with a Windows 10 Dell XPS touchscreen.
DAW: Ableton 9.5, Cubase Essentials, and Stagelight.
Old school midi gear: Oberheim MC-3000, Roland D-550, JV-2080, JP-8080, JD-800, VSynth, VR-760, Novation Supernova, Moog Little Phatty 1, DSI Prophet 08pe.

Initially, I've had no problems with this unit, until I began using Ableton. Live doesn't seem to want to recognize the drivers for it. When it does, it lists them in a way that they can't be edited. I think there needs to be new drivers written for this, as I am using the current driver set. It's possible there is no driver set for win 10 yet.
Working with it in cubase is great though. Only issue is that it doesn't seem to want to allow sys ex commands to data transfer some older gear like the D-550.
The express replaced a Yamaha UX 250, and it would be lovely if I could use both, but the drivers seem to conflict.