[doveman2]

Adding "max_usb_current=1" is pretty harmless. Worst case is the USB port will swallow more current than the PSU supplies, and the voltage drop will crash the Pi, but from what you've said that seems unlikely to occur. Give it a try and see if it helps.

It didn't actually help but then I unplugged the tuner and my remote receiver and plugged them both back in again and after refreshing the web interface, I could see the tuners under Adapters and was able to start a channel.

After rebooting though, the tuners have disappeared from the Adapters section.

I created a debug log doing just that, rebooting and checking that the tuners were not shown under Adapters, then unplugging the two USB devices and replugging them into the same ports and finding that the tuners then show under Adapters: http://pastebin.com/x6YEWEup

I've pasted the System.log here as well: http://pastebin.com/pfSHXywL