Can I use the HD4 with tablets or smartphones like Samsung Galaxy or Microsoft Surface?

Absolutely! The HD4 offers wired or wireless connections to any phone or tablet using the aux audio input or Bluetooth aptX-HD. For wired connections to newer devices without a headphone jack, you'll need the correct USB-A adapter cable to connect from your tablet to the USB input on the HD4. These are generally available from the manufacturer of your tablet/smartphone, local electronic stores, or even online retailers.