Integrated with switchable voltage

Might take on an assignment oversea where they use 240V, but want to make sure I can still use it when I return. Is there one out there, prefers tube, that has voltage switching capability (without sending the unit back to manufacture)?

Not sure what speakers to partner the amp with yet, but most likely something small so amp should have at least 50 wpc.

Another option is to use step down transformer, but prefer not to go that route.