Firstly " can i connect my laptop via a dacmagic to my denon 1910 amp".
yes you can.......use the opitcal or usb to the dacmagic then some reasonable phono cables to an input on the 1910
Second
The Denon 1910 has a PURE DIRECT mode which enhances music reproduction by turning off all unwanted processors, even the screen. I think this would work for your extra couple of speakers in the other room, it works for the main speakers, my friend has this amp and it sounds very reasonable in this mode.you would have to check in your manual. The Pure Direct button can be found on the flipside of the remote control.
You didn't mention any kind of cost for the pair of speakers, if you are wall mounting you will need a pair that are unfussy about positioning.
the Wharfedale Daimond 10.1 (£200) or the Dali Lektor 1 ( £250) or 2 (£299) would be very nice. The Roth OLI 1's (£79) are very easy to postion and very clear,,,,,,but might not have the bass responce you are after.........
..............you will need to find yourself a good pair of strong, sturdy wall brackets.
I don't know if you need advice for some surround speakers or if you are sorted...
hope this helps