A cheap way to add fun to your hi-fi is to get one of the inexpensive surround sound boxes containing the Dynaquad system. David Hafler was a big fan, and offered a couple of different Dynaco boxes to create a rear channel signal. All the circuit does is create a left minus right signal and send it to a pair of rear channel speakers. If a recording was made in a large hall/cathedral/etc, the left/right stereo recording can contain out-of-phase (left minus right) information, consisting largely of hall ambiance.
Even with "mere" 2-channel recordings, a Hafler-derived rear soundfield can be quite enveloping. You hear the stage, instruments, and singers in front of you, and the sound of the venue all around you. It’s just for fun, no need to get all purist about it. 