UK to US step up/down voltage converter

Does anyone know of a step up/down device into which I can connect a UK line cord (male)  through to an aftermarket female line cord? Nothing I have been able to find has the requisite fittings. Am I missing something really obvious? This doesn't seem to me at all exotic. 
Can you clarify what you are trying to do?  Are you trying to run a 240v device on 110v electricity?  What type of device is it?  What do you mean by "aftermarket female line cord"?
I'm using a UK DAC (Cambridge Audio Azur 851D) with a hard-wired line cord; that's fit with a Schuko plug. The DAC will be powered from an Audioquest NRG 10 cord plugged into a Furman line conditioner. So the step device needs to accept the male Schuko for output at 230V, and the end of NRG 10 without prongs for input, or 110V source. 
Thanks for your response. 
This is a good site for step up/down transformers:

See my previous post on this subject. You need to make sure the DAC is not restricted to 50Hz only, don't think it is.