Yes, sort of; clearly, a definite maybe. :-) What you need to do is buy two more speakers identical to what you currently have, and wire them in series. That would do it.
The reason one cannot put another 4 ohm driver in series with it is the speaker impedance is the net result of the cabinet, diaphragm, air movement, etc. - all those nasty speaker variables defined by Thiele and Small back in the late 70's.
You are on the right track with a transformer though. Another option is simply buying a amplifier that can drive a 2 Ohm load sufficiently, Some vacuum tube amps have 2 Ohm taps, which really solves the problem - assuming it provides the power you need.
The reason one cannot put another 4 ohm driver in series with it is the speaker impedance is the net result of the cabinet, diaphragm, air movement, etc. - all those nasty speaker variables defined by Thiele and Small back in the late 70's.
You are on the right track with a transformer though. Another option is simply buying a amplifier that can drive a 2 Ohm load sufficiently, Some vacuum tube amps have 2 Ohm taps, which really solves the problem - assuming it provides the power you need.