Exhibit 10.1

EXECUTION

PNC BANK, NATIONAL ASSOCIATION

The Tower at PNC Plaza

300 Fifth Avenue

Pittsburgh, PA 15222

December 21, 2018

Black Box Corporation

1000 Park Drive

Lawrence, Pennsylvania 15055

Attention: Chief Financial Officer

Ladies and Gentlemen:

Reference is made to that certain Credit Agreement, dated May 9, 2016 (as amended, modified, supplemented or restated from time to time, including by that certain Amendment and Joinder Agreement dated August 9, 2017, that certain Second Amendment, dated June 29, 2018, and that certain Consent Agreement, dated as of November 11, 2018 (the “Consent Agreement”) and that certain Letter Agreement dated November 17, 2018, the “Credit Agreement”), by and among BLACK BOX CORPORATION, a Delaware corporation (the “Borrower”), each of the Guarantors party thereto (together with the Borrower, collectively, the “Loan Parties”), each of the Lenders party thereto (the “Lenders”), and PNC BANK, NATIONAL ASSOCIATION (“PNC”), in its capacity as administrative agent for the Lenders under the Credit Agreement (in such capacity, the “Administrative Agent”). Capitalized terms used but not otherwise defined herein shall have the meaning set forth in the Credit Agreement.

The Borrower has entered into that certain Agreement and Plan of Merger, dated as of November 11, 2018 (as amended from time to time in accordance with the terms of the Consent Agreement, the “Merger Agreement”), providing for, among other things, the commencement of a tender offer by Host Merger Sub Inc. (“Merger Sub”) to purchase any and all of the outstanding shares of Common Stock, par value $0.001 per share, of the Borrower (“Shares”), at a price of $1.08 per Share, and, as soon as practicable following the Acceptance Time (as defined in the Merger Agreement), the merger of Merger Sub with and into the Borrower in accordance with Delaware General Corporation Law, with the Borrower as the surviving entity.

The Borrower and the other parties to the Merger Agreement have entered into an amendment to the Merger Agreement (the “Amendment”), pursuant to which such parties have agreed to increase the Offer Price (as defined in the Merger Agreement) by $0.02 to a total Offer Price of $1.10.

Under the terms of the Consent Agreement, any amendment or modification of the Merger Agreement, without the written consent of the Administrative Agent, in a manner that is materially adverse to the Administrative Agent or the Lenders, which includes any amendment or

modification that would result in an increase to the Offer Price as in effect on November 11, 2018, constitutes a “Consent Termination Event” under the Consent Agreement. The Borrower and the other Loan Parties have therefore requested that the Administrative Agent consent to the Amendment, effective as of immediately prior to the execution and delivery of the Amendment. The Borrower and the other Loan Parties have further requested that the Administrative Agent modify the “Termination Date” under the Consent Agreement in accordance with Section 8(c) thereof.

Accordingly, effective as of immediately prior to the execution and delivery of the Amendment, but subject to the satisfaction of the following conditions: (i) the execution of this Letter Agreement by the Administrative Agent and each of the Loan Parties and (ii) payment for all fees, costs and expenses of the Administrative Agent, Issuing Lender and Lenders that are required to be reimbursed under the Credit Agreement and the other Loan Documents within one (1) Business Day following delivery of an invoice or invoices for services rendered and costs incurred through the date hereof, the Administrative Agent and each of the Loan Parties hereby agree as follows:

“This Consent shall be null and void (except for the provisions of Sections 6 through 9 and 11 through 14) upon the earliest to occur of (a) the institution by the Borrower of a Relief Proceeding, (b) the occurrence of a Consent Termination Event that has not been waived in writing by the Administrative Agent in its sole discretion and (c) January 17, 2019 (unless extended by the Administrative Agent and the Required Lenders in their sole discretion) (such earlier date, the “Termination Date”).”

Except as expressly modified by the terms hereof, all of the terms and conditions of the Consent Agreement, the Credit Agreement and the other Loan Documents are hereby reaffirmed and shall continue in full force and effect as therein written.

Please countersign this letter agreement below to evidence the Loan Parties’ acknowledgment and agreement with respect to the foregoing. This letter agreement may be executed in any number of counterparts and by different parties hereto on separate counterparts, all of which, when so executed, shall be deemed an original, but all such counterparts shall constitute one and the same agreement. Any signature delivered by a party by facsimile or other form of electronic transmission shall be deemed to be an original signature hereto.

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EXHIBIT A

[AMENDMENT]

AMENDMENT NO. 1

TO AGREEMENT AND PLAN OF MERGER

THIS AMENDMENT NO. 1 (this “Amendment”) to the Agreement and Plan of Merger is made and entered into effective as of December 20, 2018, by and among AGC Networks Pte Ltd., a company organized under the laws of Singapore (“Top Parent”), BBX Main Inc., a Delaware corporation and a wholly owned Subsidiary of Top Parent (“Parent”), BBX Inc., a Delaware corporation and a wholly owned Subsidiary of Parent (“BBX Intermediate”), Host Merger Sub Inc., a Delaware corporation and a wholly owned Subsidiary of BBX Intermediate (“Merger Sub”; together with Top Parent, Parent and BBX Intermediate, the “Parent Entities” and each, a “Parent Entity”), and Black Box Corporation, a Delaware corporation (the “Company”).

WHEREAS, the Parent Entities and the Company entered into that certain Agreement and Plan of Merger, dated as of November 11, 2018 (as amended from time to time, the “Merger Agreement”), providing for, among other things, the commencement of a tender offer by Merger Sub to purchase any and all of the outstanding shares of Common Stock, par value $0.001 per share, of the Company (the “Shares”), at a price of $1.08 per Share, and, as soon as practicable following the Acceptance Time, the merger of Merger Sub with and into the Company in accordance with the DGCL, with the Company surviving the Merger as a wholly-owned Subsidiary of BBX Intermediate;

WHEREAS, pursuant to Section 9.1 of the Merger Agreement, prior to the Acceptance Time, the Merger Agreement may be amended by the parties thereto by action taken or authorized by or on behalf of their respective boards of directors, at any time prior to the Closing Date; and

WHEREAS, upon the authorization and recommendation of the parties’ respective boards of directors, the parties have determined that it is in the best interest of the Offer and the Transactions to amend the Merger Agreement to increase the Offer Price by $0.02, to a total Offer Price of $1.10.

NOW, THEREFORE, in consideration of the mutual agreements contained herein, the Parent Entities and the Company hereby agree to amend the Merger Agreement as follows:

“at a price of $1.10 per Share, net to the holder thereof, in cash, without interest thereon (such amount, or any higher amount per Share that may be paid pursuant to the Offer in accordance with this Agreement, being hereinafter referred to as the “Offer Price”), all upon the terms subject to the conditions set forth herein.”

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IN WITNESS WHEREOF, the parties hereto have caused this Amendment to be executed by their respective officers thereunto duly authorized as of the date first above written.