[sdiy] Step-down transformer (in the USA)

[jhaible at jhaible.de]

Can anybody recommend a good autotransformer / step-down transformer  
from an US-based mail order shop?

No open frame model, but in an enclosure with the plugs attached,  
ready to connect a European musical instrument (230V) to the US mains  
(115V).
Power rating of 50W would be plenty.

Easy to handle for somebody who doesn't solder.

(I tried Mouser and Allied already.)

Thanks in advance,

JH.