I have heard Vandies many times, one occasion with a pair of huge class A Sugden Masterclass mono amps belting out lovely sound at high level from the model 2 in a large hotel room at the closing of last day at a show. They filled that room beautifully and without any sign of strain.
Take cognisance of the suggestions to improve the source. A computer with Dragonfly output is going to disappoint. Replacing your speakers as some have advised will merely give you a different perspective on the inadequacies of your existing source. The most expensive speakers introduced to your existing kit will simply more accurately reveal your problems.
The Vandies may not be for you but right now IMO you are not in a position to make that call. It's the well known garbage-in-garbage-out story.