Can I use the USB input on the A2+ Wireless with other tablets or smartphones like Samsung Galaxy or Microsoft Surface?

Yes! If your tablet or smartphone has a USB output and supports USB audio (refer to the manufacturers’ documentation), then it will work with A2+ Wireless's USB input. You'll most likely also need an OTG adapter cable to connect from your tablet to the USB input on the A2+ Wireless. These are generally available from the manufacturer of your tablet/smartphone, local electronic stores, or even online retailers.