I would say leave the elite go for k281
And yes u can use 2.0 usb in 3.0
Here are the official specs from cooler master site it says it supports hd audio
http://www.coolermaster.com/product/Detail/case/mid-tower/k281.html
Model RC-K281-KKN1
Available Color Full Midnight Black
Materials SGCC (0.5T), HIPS Plastic, Mesh front bezel
Dimension (W x H x D) 219 x 416 x 487mm / 8.6 x 16.3 x 19.1 inch
Net Weight 5.0 kg / 11.0 lbs
M/B Type Micro-ATX, ATX
5.25" Drive Bays 3 (exposed)
3.5" Drive Bays 7 (hidden)
2.5" Drive Bays 1 (hidden)
I/O Panel USB 3.0 x 2 (internal), Mic x 1, Audio x 1 (supports AC97 / HD Audio)
Expansion Slots 7
Cooling System Front: 120mm red LED fan x 1
Rear: 120mm black fan x 1
Side: 120mm fan x 1 (optional)
Power Supply Type Standard ATX PS2
Maximum Compatibility VGA card length: 315mm / 12.4 inch
CPU cooler height: 162mm / 6.4 inch