<PAGE>   1
                                                                   EXHIBIT 10.26


        THIS SECOND LEASE AMENDMENT ("Second Amendment") dated this 21st day of
March, 1997, by and between Klopfer Associates Limited Partnership, a Maryland
limited partnership (hereinafter referred to as the "Landlord") and Polk Audio,
Inc., a Maryland corporation (hereinafter referred to as the "Tenant").

        WITNESSETH, THAT WHEREAS Landlord and Tenant entered into a certain
Lease Agreement dated September 23, 1985 (hereinafter referred to as the
"Lease"); and

        WHEREAS Landlord and the Tenant amended the said Lease by means of a
Lease Amendment dated September 23, 1993 (hereinafter referred to as the "First
Amendment"); and

        WHEREAS the parties desire to redefine the Leased Premises, to extend
the term of the Lease and to make certain other changes thereto;

        NOW THEREFORE for and in consideration of the mutual covenants and
other undertakings herein contained, the parties do hereby agree to further
amend the Lease and the First Amendment as follows:

        1.  Term.  The term of the Lease shall be extended to the last day of
May, 2007. Section 5 of the First Amendment shall remain in full force and
effect.

        2.  Leased Premises.  Effective as of June 1, 1997, or on the actual
effective commencement date of the lease dated 17th September, 1996 by and
between Landlord and Sinai Hospital of Baltimore, Inc., as further amended by
an Amendment dated 18th February, 1997 (collectively, the "Sinai Lease"),
whichever shall be later (the "Effective Date"), the Leased Premises shall
constitute 76,000 square feet at the west end of the building addressed as 5601
Metro Drive, Baltimore MD 21215, as shown outlined and crosshatched in red in
Section 1 of the attached plat marked Exhibit "A", together with ninety five
(95) parking spaces set aside for the exclusive use of the Tenant, as outlined
and crosshatched in red in Section 2 of Exhibit "A", together with easements to
use in common with others the private access driveways and rear exterior paved
loading areas of the Property, (such interior building space, reserved parking
areas and easements leased hereby being hereinafter collectively referred to as
the "Leased Premises"). Tenant shall not use parking areas or loading docks
other than those reserved for its exclusive use.

        3.  Rent.  The annual base rental payable for the Leased Premises, as
set forth in Section #2 of the Lease, commencing on the Effective Date, shall
be FIVE HUNDRED THIRTY FIVE THOUSAND DOLLARS ($535,000.00) for the Leased
Premises (as defined in the preceding Section hereof) on an "as-is" basis,
payable in equal monthly installments of FORTY FOUR THOUSAND FIVE HUNDRED
EIGHTY THREE AND 33/00 DOLLARS ($44,583.33) each (the "Base Rental"). In
addition thereto Tenant shall be liable for additional rent taxes, insurance
and maintenance costs as provided in Sections 4 and 5 hereof and as provided in
the Lease (except as expressly modified herein), including without limitation
Sections 7, 8, 9, 10, 11, 18 and 32 hereof.




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<PAGE>   2
Second Amendment to Lease
Klopfer Associates Ltd. Partnership/Polk Audio, Inc.
page 2


        4.  Escalation.  The Base Rental shall be adjusted on January 31 of
each year starting in 1998, in the manner set forth in Section 9 of the Lease,
to reflect changes in the Consumer Price Index from October 1996 to October
1997, and in a like manner annually thereafter.

        5.  Brokerage and Other Expenses.  Tenant shall be responsible for
direct payment of brokerage commissions due to Miller Corporate Real Estate
Services, Inc. relating to the Sinai Lease, as well as all other expenses
incident to the initial implementation of the Sinai Lease, including without
limitation the cost of construction of all demising walls and other tenant
improvements, legal fees, architectural and engineering fees and incidental
costs such as those related to zoning actions.

        6.  Deletions to First Amendment.  Sections 7 and 8 of the First
Amendment are hereby deleted in their entirety.

        7.  Other Provisions.  Except as expressly modified or deleted herein,
all other provisions of the Lease and the First Amendment shall remain in full
force and effect. Except as otherwise provided herein, all terms used herein
shall have the same meaning ascribed to them in the Lease and/or the First
Amendment.

        8.  Conditions Precedent.  Landlord's willingness and ability to enter
into the Second Amendment is expressly conditioned on (i) the final
effectiveness of the Sinai Lease (as described above) and (ii) obtaining the
consent of NationsBank to this Amendment. If before April 15, 1997 the Sinai
Lease shall not have become effective and noncancellable by the tenant therein
in accordance with its terms, or if the Landlord shall not have obtained the
consent of NationsBank in writing to the Sinai Lease or to this Second
Amendment, then this Second Amendment shall be null and void and the Lease and
the First Amendment shall continue unmodified in full force and effect. If
Landlord has reason to believe that either or both of the foregoing conditions
precedent is not likely to be satisfied, it shall promptly notify the Tenant
thereof.

        IN WITNESS WHEREOF, each of the parties hereto has caused its duly
authorized officer or partner to execute and enseal this Second Amendment, on
the year and day first above written.




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<PAGE>   3
Second Amendment to Lease
Klopfer Associates Ltd. Partnership/Polk Audio, Inc.
page 3


WITNESS/ATTEST:                          LANDLORD:
                                         KLOPFER ASSOCIATES L.P.


/s/ DEBORAH J. SMITH                     /s/ GEORGE M. KLOPFER
-------------------------------          -----------------------  (SEAL)
                                         by: George M. Klopfer
                                             General Manager


WITNESS/ATTEST:                          LANDLORD:


                                         POLK AUDIO, INC.
/s/ DEBORAH J. SMITH                     /s/ JAMES M. HERD
-------------------------------          ----------------------------- (SEAL)
                                         by: James M. Herd, President


Consent given to
Second Amendment to Lease:
NATIONSBANK, N.A.


-------------------------------------                                         
by: Andrew John, Senior V.P.   (date)


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