Look it over carefully for a nameplate.
Many switcher power supplies are "universal" and will run from 90 to 270 volt input.
A quality subwoofer more likely has a transformer power supply not a switcher.
You'll have to verify the transformer has taps for 230 volts and is rated for 50 hz.
Sometimes quality gear has switches that'll allow you to select transformer taps for Euro input voltage. Dual primary windings would be paralleled for 120, series for 230.
Look your unit over carefully.
I see the owners manual here
http://www.energy-speakers.com/docs/common/TK-CLASSI-5-1/TK-CLASSI-5-1_OM.pdf
mentions a 120 volt US version
and gives an address for inquiries
http://www.energy-speakers.com/support/ which directs you to
http://support.klipschgroupinc.com
i'd think Klipsch name indicates quality... but one can't tell anymore.
Lastly I'm confused by this review:
http://www.pcmag.com/article2/0,2817,2405955,00.asp
Note that unlike most of the speakers we test, the Energy Take Classic 5.1 is unpowered. It's meant to be paired with a receiver, integrated amplifier, or separate pre-amp and amplifier components in a full-sized living room or den system. This is the more traditional way of putting together an audio system, which dates back decades, but I just wanted to point that out up front.
and i find no mention of power in its specifications. And spec sheet says it connects via heavy binding posts, like old fashioned speakers sans amplifier.
Just what the heck is this thing? Why does it have a power cord at all?
Is the light only cosmetic?