2) Use an autoformer: it transforms from one impedance to another:
http://www.zeroimpedance.com/
or 'matchit' from parts express:
http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=302-305

I have not personally used either of these, but I do use McIntosh amplifiers which incorporate autoformers to drive low impedance loads such as my DIY ribbon at 1 ohm.

• http://www.zeroimpedance.com/