"A Congressional committee must meet three requirements for its subpoenas to be 'legally sufficient.' First, the committee's investigation of the broad subject area must be authorized by its chamber; second, the investigation must pursue 'a valid legislative purpose' but does not need to involve legislation and does not need to specify the ultimate intent of Congress; and third, the specific inquiries must be pertinent to the subject matter area that has been authorized for investigation." Wilkinson v. United States.
So, in this case an impeachment inquiry is under the jurisdiction of the Judiciary committee not the Intelligence committee. Moreover, there has been no authorization by the House to conduct an Impeachment investigation. Finally, there has been no particular subject matter specifically authorized at all.
The answer: HOLD A VOTE!