<PAGE>   1
                                                                 Exhibit 10.29


                                    AMENDMENT
                                       OF
                         CONSULTING AND OPTION CONTRACT

This is an Amendment to the Contract is between Rockford Corporation, an Arizona
corporation ("Rockford") and Grisanti, Galef & Goldress, Inc., a Nevada
corporation ("3G"). Rockford and 3G agree as follows:

1     RECITALS.

      1.1   Rockford Business. Rockford manufactures and distributes high
            quality car and professional audio products under various brand
            names including "Rockford-Fosgate", "Hafler Professional", "Rockford
            Acoustic Designs", and "Connecting Punch."

      1.2   3G Consulting Services. 3G is in the business of providing executive
            and other consulting services. 3G has provided services to Rockford
            pursuant to (a) a letter agreement dated February 8, 1992, and
            accepted by 3G on February 10, 1992, (b) a Consulting and Option
            Contract dated March 10, 1993, and (c) and Amendment and Renewal of
            Consulting and Option Contract dated as of August 1, 1995 (the
            "Prior Contract"). Pursuant to the Prior Contract, 3G has provided
            executive and consulting services to Rockford through W. Gary Suttle
            ("Suttle") and other 3G's associates.

      1.3   Amendment to Agreement. 3G, Rockford, and Suttle have now agreed to
            amend the Prior Contract in order that Rockford may directly employ
            Suttle as a full time employee.


2     AMENDMENT OF PRIOR CONTRACTS. Sections 2 and 3 of the Prior Agreement are
      deleted in their entirety. For the remaining term of the Prior Agreement,
      3G will provide executive and advisory services to Rockford through its
      associates other than Suttle (with Rockford's advance approval). 3G
      consents to Rockford's hiring of Suttle as a full time employee of
      Rockford and waives payment of the fee otherwise required by Section 13 of
      the Prior Contract in connection with Suttle's employment.

      2.1   Nature of Required Services. Rockford and 3G will from time to time
            agree on the exact nature of the consulting services to be performed
            under the Contract.

      2.2   Director. 3G will designate its associate Jerry Goldress to serve as
            a Director of Rockford.

      2.3   Compensation of 3G Associates. 3G will pay, and bear exclusively,
            all compensation of Goldress and other 3G associates working on the
            Rockford engagement, except that Rockford will pay Goldress
            directors' fees and other compensation consistent with Rockford's
            compensation policies for its directors.
<PAGE>   2
3     COMPENSATION AND EXPENSES. Sections 5.1, 5.2, 5.3, and 5.5 of the Prior
      Agreement are deleted in their entirety. Rockford and 3G will negotiate
      and approve the compensation payable to 3G for its services on a project
      by project basis for the remaining term of the Prior Contract. Sections
      5.4 and 5.6 are not amended and remain effective.

4     STOCK OPTION. As consideration for Jerry Goldress service as a director
      and for 3G's waiver of the placement fees under Section 13, Rockford will
      grant to Jerry Goldress as a director, and under the Rockford 1997 Stock
      Option Plan, options to purchase an additional 5,000 shares of Rockford
      Common Stock under the terms of the plan.

5     NO OTHER CHANGES. Except as set forth herein, the Prior Contract remains
      effective without change and is reconfirmed by the parties.

6     EXECUTION AND EFFECTIVE DATE. This Amendment is effective as of January 1,
      1999.



                                    Grisanti, GALEF & GOLDRESS, Inc.



                                    By /s/
                                       ----------------------------------------
                                          Jerry Goldress, Chairman
                                          Address:    P. O. 5240
                                                      114 Robert
                                                      Incline Village, NV 89450

                                    Rockford Corporation



                                    By /s/
                                       ----------------------------------------
                                          W. Gary Suttle, President
                                          Address:    648 South River Drive
                                                      Tempe, Arizona 85281


                                      -2-