That's how you need to test your current gear. This way you can reasonably know that the speakers still work like they used to and the receiver would naturally be the problem. YMMV. Find a retailer/etailer with liberal return policy if you can't borrow from a friend or family member.

That said, that soundbar was close to $700 new, if I recall correctly(!?). Wow. Skip that nonsense and get some entry level proper surrounds & sub. It will sound remarkably if not incredibly better since you would gain the ability to properly position and physically separate all the speakers to fit your particular (unique) HT/listening space. If budget is an issue, grab some Energy Take Classic 5.1s for half the price of that soundbar to see what I mean.