jhlui1

The 1/4 output on the SonicPort (non VX model) is a TRS output (tip-ring-sleeve - looks like a 1/4" headphone plug) compatible output jack which can also be run in mono mode (when a standard mono 1/4 plug is inserted, it detects the shorting of the ring signal and just bridges the output).

It's unbalanced out.  But the two ways you can get your signal to the Alesis would be a 1/4 TRS to 1/4 dual mono (TS - called a tip-sleeve) cable (looks like this one: https://www.amazon.com/CablesOnline-Stereo-Audio-Cable-AV-YS15/dp/B00E3BN8IS)

Or you could use the headphone output and use 1/8" TRS to dual-1/4 TS.

Or you could even use a 1/8" TRS to dual XLR (https://www.amazon.com/Hosa-CYX-403M-XLR3M-Stereo-Breakout/dp/B000068OEP)

Can't really control Left to Right balance, or output levels without the App (you can use the monitor's volume control, if needed), but it works.

Key thing is as long as you have 2 speakers, no reason not to keep the signal stereo on the way out to the monitors (don't bother with a 1/4" TS to dual 1/4" TS splitter cable.)

My 2nd unit Sonicport VX (purchasing via Line6's refurb program) works fine with IOS 10.2 on an iPhone SE. 

That being said, the 1st unit I received actually was pretty much the same thing @Bipai described - was okay working via USB, but the Lightning port (or 30-pin, because I also tested it with an older iPod Touch and iPad 2) was completely non-functional.

In basic testing, I noticed if you are just supplying USB power to the Sonicport without connecting to either an iPhone, nor an actual PC/Mac, the unit won't show any signs of working (you can plug in a headset, but you won't hear anything.)

Until it is recognized as an ASIO device on a PC, it will not enable even the direct-monitoring switch.

Or if you then plug it into an Apple device (Lightning or 30-pin) with a compatible App running (important, because if you aren't actually running a compatible App while trying to use the Sonicport, it will similarly appear completely dead. (and per my prior finding, if you try to connect the Lightning AND the USB simultaneously, the USB side will be disabled for playback/recording (meaning the PC/Mac will not detect the device, and won't enable it until you disconnect the Apple device.)

Make sure you at least download and run the Line6 Mobile POD (you don't have to pay for the App - leave it in Trial Mode.) After a few minutes (took me about 5) of being connected to the Sonicport, the Mobile POD App will unlock itself and all the preset tones should unlock - but it doesn't happen instantly upon the first plug-in.  Before the App fully unlocked, my Sonicport initially appeared non-responsive on the Apple device, as well. Then after a minute or two, I saw the device show up in the Settings screen of the App.  And a few more minutes later, all of the lock icons disappeared (you may need to be connected to the Internet for this to happen, whether cellular or WiFi.)

Just validated the same solution for the Windows 10 x64 (bit) issue with the ASIO drivers.

v1.76 didn't work on 64-bit Windows 10 initially, worked fine with WIndows 7 x64.

v1.52 worked fine - shows up immediately in the Control Panel -> USB Devices -> Sonicport VX

I did Run as Administrator... and I didn't uninstall 1.76 before running the 1.52 installer - I just sent the install to the same location.

And shows up in Audacity as both an available Recording and Playback device.

And I checked Reaper (x64) v5.30 Windows - working with both the Line6 ASIO 1.52 driver and the ASIO4ALL driver.

HOWEVER... I notice I currently cannot use both my AmpliFi ASIO Inputs at the same time as the Sonic Port (if I plug one USB in, the 2nd one will cut off the 1st one.) using the older 1.52 driver. Simultaneous use requires upgrading to the 1.76 Sonic driver and the 1.77 AmpliFi driver.  When both are updated, you can then use the AmpliFi to record while the Sonic VX is your FX processor.

AND, I notice that while I can get the Mobile POD on the iPhone working with output via the Sonic Port Line Outs (to address another observation about latency, I find the latency when trying to record from the Sonic out routed back into another ASIO line-in, such as my AmpliFi, or via a Presonus I/O, .)

The Sonic VX will disable the ASIO Recording and Playback inputs (to Windows) if both the USB to PC and Lightning are used simultaneously.  If I then disconnect the iPhone from the Sonicport, the ASIO/USB port re-activates again. This is true regardless of driver version, and in both Windows 7 and 10.  I think this is by design.  The USB port is only providing pass-through power if the Lightning is enabled (which answers someone else's question about trying to use the iPhone/iPod as an FX loop while recording in Windows (you would need another interface to connect the line-outs from the Sonic VX to the PC/Mac; in my case, I can use the AmpliFi as a route back into the PC to record the post-effects signal by the iPhone.)

Also both Recording and Playback devices show up in the Control Panel -> Sound as long as you don't have the Lightning port connected.

And of course, worked fine on Lightning to my iPhone SE on iOS 10.1.1 (about to see what happens with iOS 10.2...  And it looks fine so far with 10.2 on an SE.)