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                                                                   Exhibit 10.51


            CONFIDENTIAL TREATMENT REQUESTED BY ROCKFORD CORPORATION




                              SIMPLEDEVICES, INC.

                        -------------------------------

                          SECOND AMENDED AND RESTATED

                                VOTING AGREEMENT

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            CONFIDENTIAL TREATMENT REQUESTED BY ROCKFORD CORPORATION


                  SECOND AMENDED AND RESTATED VOTING AGREEMENT

            THIS SECOND AMENDED AND RESTATED VOTING AGREEMENT (this
"AGREEMENT"), by and among SimpleDevices, Inc. (the "COMPANY"), the undersigned
holders of the Company's Common Stock (collectively, the "COMMON STOCKHOLDERS"),
the undersigned holders of the Company's Series A Preferred Stock, (the "SERIES
A STOCKHOLDERS"), and the undersigned holders of the Company's Series B
Preferred Stock, (the "SERIES B Stockholders") (collectively, the "PREFERRED
STOCKHOLDERS") and Rockford Corporation ("ROCKFORD") is entered into on this
16th day of October, 2002.

            WHEREAS, the Company, the Common Stockholders and the Preferred
Stockholders are parties to that certain Amended and Restated Voting Agreement
dated as of May 23, 2001 (the "PRIOR VOTING AGREEMENT");

            WHEREAS, the Company and the parties to the Prior Voting Agreement
desire to amend, restate and replace the Prior Voting Agreement in its entirety
with this Agreement pursuant to Section 5 of the Prior Voting Agreement;

            WHEREAS, in order to induce Rockford to purchase shares of the
Company's Common Stock, the parties hereto have indicated their willingness to
enter into this Agreement upon the terms and conditions set forth below;

            WHEREAS, upon consummation of the share purchase transaction between
the Company and Rockford, the Series A and Series B Preferred Stock held by the
Preferred Stockholders shall be automatically converted to Common Stock and the
Preferred Stockholders shall have the rights of Common Stockholders; and

            WHEREAS, the parties hereto enter this Agreement for the additional
purpose of confirming the arrangements for election of directors;

            NOW, THEREFORE, in consideration of the mutual promises and
covenants hereinafter set forth, the receipt and sufficiency of which is hereby
acknowledged, the parties agree as follows:

            The Prior Voting Agreement is terminated and amended, restated and
replaced in its entirety with this Agreement effective upon the execution of
this Agreement by the Company and the required majority in interest of the
Common Stockholders, the Preferred Stockholders, and Rockford.

      1. Agreement to Vote. The Common Stockholders, the Preferred Stockholders,
and Rockford (each a "HOLDER" and collectively the "HOLDERS")hereby agree to
vote all shares of Common Stock, Series A Preferred Stock, and Series B
Preferred Stock, and any other shares of voting securities of the Company now
owned or hereafter acquired or controlled by them (collectively, the "VOTING
SECURITIES") as follows:
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            CONFIDENTIAL TREATMENT REQUESTED BY ROCKFORD CORPORATION


            (a) Board of Directors Composition. The Common Stockholders and
Investors shall vote or act with respect to the Voting Securities so as always
to elect the directors of the Company in the following manner:

                  (1)   *****;

                  (2)   *****;

                  (3)   *****.

            (b) Removal of Directors. The Common Stockholders, the Preferred
Stockholders, and Rockford shall vote or act with respect to the Voting
Securities so as to remove any director designated for removal by the Holder or
Holders of the shares entitled to fill a vacancy occurring upon the removal of
such director.

            (c) Size of Board. The Holders agree not to vote or act with respect
to the Voting Securities, and the directors agree not to vote as directors of
the Company, so as to change from five (5) the number of directors on the Board
of Directors of the Company, unless Holders representing more than two-thirds
(2/3) of the then outstanding Voting Securities agree.

      2. Further Assurances. Each of the Holders and the Company agree not to
vote any shares of Company stock, or to take any other actions, that would in
any manner defeat, impair, be inconsistent with or adversely affect the rights
of the parties under Section 1 of this Agreement. The Company agrees to use
reasonable effort to ensure that the rights granted to the parties hereunder are
effective and that the parties enjoy the benefits thereof. Such actions include,
without limitation, the use of reasonable effort to cause the nomination and
election of the directors as provided in Section 1 above.

      3. Successors in Interest. The provisions of this Agreement shall be
binding upon the successors in interest to any of securities of the Company held
by any party to this Agreement and their successors and assigns. The Company
shall not permit the transfer of any of the securities on its books or issue new
certificates representing any such securities unless and until the person(s) to
whom such shares are to be transferred shall have executed a written agreement,
substantially in the form of this Agreement, pursuant to which such person
becomes a party to this Agreement and agrees to be bound by all the provisions
hereof as if such person was a party hereunder.

      4. Termination. This Agreement shall terminate upon the earlier of:

            (a) the date the Company consummates an underwritten public offering
of its Common Stock under the Securities Act of 1933, as amended; or

            (b) The sale of all or substantially all of the assets of the
Company; or

            (c) The closing of an acquisition of the Company by another
corporation or entity by a consolidation or merger in which the holders of the
Company's outstanding voting


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            CONFIDENTIAL TREATMENT REQUESTED BY ROCKFORD CORPORATION


stock immediately prior to such transaction own, immediately after such
transaction, securities representing less than 50% of the voting power of the
corporation or other entity surviving such transaction.

      5. Board Visitation Rights. The parties hereto hereby agree that ***** and
**** shall have the following board visitation rights:

            (a) Unless the Company's Board of Directors determines, in its sole
discretion, that it would be inappropriate to do so for reasons of
confidentiality or potential conflicts of interest, the Company shall invite one
representative of *** and *** to attend all meetings of its Board of Directors
in a nonvoting observer capacity and, in this respect, shall give such
representative copies of all notices, minutes, consents, and other
non-confidential material that it provides to its directors. Such representative
may participate in discussions of matters brought to the Board of Directors; and

            (b) *** and *** agree, and each representative of *** and *** will
agree, (i) to hold in confidence and trust and not use or disclose any
confidential information provided to or learned by it in connection with its
rights under this Agreement unless *** and or *** and their representatives are
required to disclose said confidential information by applicable law, order of
government agency or self-regulatory body, provided, however, that *** and or
*** and their representatives shall to the extent possible give reasonable prior
notice, to the Company of said disclosure and shall reasonably cooperate with
the Company to limit the scope of said disclosure, and (ii) that ***'s and or
***'s representative may be excluded from, and shall not be delivered written
information with respect to, any portion of a meeting of the Board of Directors
in which management intends to disclose confidential business information
regarding (a) product strategy, pricing, technology, customer relationships or
similar matters if management determines that the disclosure of such information
to ***, *** or their representatives would be detrimental to the Company's
business, or (b) joint marketing arrangements, joint development projects,
mergers, acquisitions, joint ventures or strategic alliances if management
determines that disclosure of such information to *** or *** would be
detrimental to the Company's business. The provisions of this Section 4(b) shall
not apply with respect to any confidential information that *** or *** can
document (i) is (through no improper action or inaction of its own or any
affiliate, agent, consultant or employee) generally known to the public, or (ii)
was rightfully in its possession or rightfully known by it prior to receipt from
the Company, or (iii) was rightfully disclosed to it by a third party without
restriction.

      6. Effect of Conversion of Preferred Stock. Upon consummation of the share
purchase transaction between the Company and Rockford, the Series A and Series B
Preferred Stock held by the Preferred Stockholders shall be automatically
converted to Common Stock and the Preferred Stockholders shall have the rights
and obligations of Common Stockholders.

      7. Amendments and Waivers. Any term hereof may be amended and the
observance of any term hereof may be waived (either generally or in a particular
instance and either retroactively or prospectively) only with the written
consent of (a) the Company, (b) the Holders and their respective successors and
assigns, holding at least two-thirds (2/3) of the shares of


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            CONFIDENTIAL TREATMENT REQUESTED BY ROCKFORD CORPORATION


capital stock of the Company and their respective successors and assigns,
provided, however, that any amendment which imposes additional liabilities or
obligations on any Holder beyond the initial subject matter of this Agreement
shall not be effective without the prior written consent of such Holder or
Holders. Any amendment or waiver so effected shall be binding upon the Company
and the Holders and all of their respective successors and assigns whether or
not such party, assignee or other stockholder entered into or approved such
amendment or waiver.

      8. Enforceability/Severability. The parties hereto agree that each
provision of this Agreement shall be interpreted in such a manner as to be
effective and valid under applicable law. If any provision of this Agreement
shall nevertheless be held to be prohibited by or invalid under applicable law,
(a) such provision shall be invalid only to the extent of such prohibition or
invalidity, without invalidating the remainder of such provision or the
remaining provisions of this Agreement, and (b) the parties shall, to the extent
permissible by applicable law, amend this Agreement, so as to make effective and
enforceable the intent of this Agreement.

      9. Governing Law. This Agreement shall be governed by and construed under
the laws of the State of Delaware, without regard to the conflict of laws
provisions thereof.

      10. Counterparts. This Agreement may be executed in counterparts, each of
which shall be deemed an original, but all of which together shall constitute
one and the same instrument.

                            [SIGNATURE PAGES FOLLOW]


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            CONFIDENTIAL TREATMENT REQUESTED BY ROCKFORD CORPORATION


            IN WITNESS WHEREOF, the parties hereto have executed this Agreement
as of the day and year hereinabove first written.

                                      SIMPLEDEVICES, INC.


                                      By:       ________________________________
                                                Louis S. Hughes, III
                                                President and Chief Executive
                                                Officer

                                      Address:  Bay View Plaza
                                                2121 El Camino Real, 2nd Floor
                                                San Mateo, CA 94403




        [SIGNATURE PAGE - SECOND AMENDED AND RESTATED VOTING AGREEMENT]
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            CONFIDENTIAL TREATMENT REQUESTED BY ROCKFORD CORPORATION


                                            ROCKFORD CORPORATION, an Arizona
                                            corporation


                                            By:        _________________________
                                            Name:      W. Gary Suttle
                                            Its:       President and CEO

                                            By:        _________________________

                                            Name:      _________________________
                                            Its:       Secretary

                                            Address:   546 South Rockford Drive
                                                       Tempe, AZ 85281

                                            Phone:     (480) 967-3565
                                            Facsimile: (480) 967-8132


           [SIGNATURE PAGE TO AMENDED AND RESTATED VOTING AGREEMENT]