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                                                                    EXHIBIT 4.3

                                 EUPHONIX, INC.
                      AMENDMENT TO SECURED PROMISSORY NOTE
                             DATED FEBRUARY 22, 2000

        This agreement dated November 29, 2001 (this "Amendment") amends the
Secured Promissory Note (the "Note"), dated February 22, 2000 by and among
Euphonix, Inc., a California corporation ("Borrower"), Milton Chang, Dieter
Meier, Walter Bosch, Onset Enterprise Associates, L.P., Onset Enterprise
Associates III, L.P. and Stephen D. Jackson (each an "Investor" or "Lender" and
collectively the "Investors" or the "Lenders") as amended up to the date of this
Amendment. This Amendment will become effective immediately prior to the date of
the Secured Promissory Note to be executed (the "Execution Date") in connection
with the Financing (as defined below). Capitalized terms not defined here have
the meaning set forth in the Note.

                                    RECITALS

        A. The Borrower has arranged for a debt financing of up to $6 million
(the "Financing") that is contingent on the Investors agreeing to amend the Note
to among other things, extend the maturity date and reduce the interest payable
on the Note in exchange for increasing the number of shares issuable to
Investors upon conversion of the Note and the waiver by Dieter Meier and Walter
Bosch of any claims of Borrower's alleged default under notes payable by
Borrower to Messrs. Meier and Bosch.

        B. Subsection I.6 of the Note provides that the Note may be amended by a
written instrument signed by Borrower and the Lender.

        NOW, THEREFORE, in consideration of the mutual promises set forth
herein, and for other good and valuable consideration (including that recited in
Paragraph A. above), the receipt and sufficiency of which is hereby
acknowledged, the parties agree as follows:

                              ARTICLE I: AMENDMENTS

        1. Subsection B of the Note is hereby amended by replacing the first
sentence with the following sentences:

        "Interest shall accrue with respect to Advances on the principal sum
        hereunder at the per annum rate of eight percent (8%), net of any
        deductions or withholding taxes. The reduction in interest payable will
        be retroactive to the date of each advance."

        2. Subsection C.1 of the Note is hereby amended by replacing it in its
entirety by the following new subsection:

        "Scheduled Payment. Subject to other provisions of this Note, the
        outstanding principal sum of this Note, together with the accrued
        interest thereon, shall be due and payable on December 31, 2003."


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        3. Subsection C.5(a)(ii) of the Note is hereby amended by replacing it
in its entirety by the following new provision:

        "(ii) the lower of: (A) $0.35 or (B) the average of the closing price
        per share for the 3 trading days immediately preceding the Execution
        Date, provided, however that the price per share as determined in this
        clause (B) can be no lower than $0.02 per share."

        4. Subsection C.5(c) of the Note is hereby amended by replacing it in
its entirety by the following new provision:

        "Notwithstanding anything herein to the contrary, unless waived by the
        holders of a majority of the outstanding principal amount of this Note,
        the outstanding principal sum from all Advances as of the date thereof
        and all accrued interest thereon, shall accelerate and become due and
        payable in full, according to each Investor's Pro Rata Share upon the
        occurrence of any of the following (each, a "Transaction"): (i) the
        sale, transfer or other disposition of any of Borrower's material assets
        (not including product inventory for sale to customers in the ordinary
        course of business), (ii) the acquisition of voting control in excess of
        50% of Borrower by persons (other than the Investors), or (iii) the
        merger or consolidation of Borrower with or into another entity whereby
        the holders of Borrower's voting securities prior to such merger or
        consolidation hold less than 50% of the voting securities of the
        surviving entity. Notice of any such Transaction shall be provided to
        the Investors fourteen (14) calendar days prior to the consummation of
        any such Transaction and, notwithstanding anything to the contrary
        contained elsewhere in this Note, Investors may exercise their rights of
        conversion during such 14-day period."

        5. The Note is hereby amended by adding in the following new provision
as new Subsection C.5(d):

        "Notwithstanding anything herein to the contrary, this Note shall not be
        convertible into shares of Common Stock as contemplated herein, until
        such time as the Borrower has obtained shareholder approval of (i) an
        amendment to the Company's Articles of Incorporation to authorize a
        sufficient number of additional shares of Common Stock for potential
        issuance upon conversion of this Note, and (ii) this Amendment. Borrower
        hereby covenants that it will hold a meeting of its shareholders, or
        otherwise seek written consents of its shareholders, as soon as
        practicable after the date of this Amendment in order to seek such
        shareholder approval. The Investors further acknowledge that: (i)
        Borrower will authorize, in its Articles of Incorporation, a total of
        150 million shares of Common Stock, of which 125 million will be
        reserved for issuance upon: (x) conversion of this Note, (y) conversion
        of the convertible promissory notes dated April 14, 2000, September 7,
        2000, December 29, 2000, March 15, 2001, and November 29, 2001, and (z)
        exercise of warrants issued pursuant to Section G.1 of the convertible
        promissory note dated November 29, 2001; and that (ii) the Investors
        cannot effect any such conversion or exercise as described in the
        foregoing clause (i) that exceeds 125 million shares unless and until
        the shareholders approve an amendment to the Articles of Incorporation
        increasing the number of authorized shares to an amount that permits
        such exercise or conversion."


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        6. Subsection G.3 of the Note is hereby deleted in its entirety.

        7. Subsection I.6 of the Note is hereby amended by replacing it in its
entirety by the following new provision:

        "Amendment Provisions. This Note may be amended by the addition or
        deletion of any provisions thereof and any rights of a Lender may be
        modified in any manner in writing by the Borrower and Lenders holding
        notes representing a majority of the principal amount under notes issued
        by the Borrower on February 22, 2000, April 14, 2000, September 7, 2000,
        December 29, 2000 and March 15, 2001; provided, however, that no such
        amendment shall, without the consent of each Lender to be affected
        thereby: (i) extend the Scheduled Payment date set forth in Subsection
        C.1, (ii) reduce the principal amount of the Note, (iii) decrease any
        interest rate payable under the Note, (iv) change the currency in which
        the Note is payable, (v) impair any rights of a holder against the
        Borrower upon any Event of Default, (vi) modify any of the conversion
        features of the Notes or increase the amounts set forth in Subsection
        C.5(a)(ii), or (vii) impair any Lenders' lien on the Borrower's assets."

        8. A new Subsection I.12 is hereby added to the Note that states in its
entirety as follows:


        "Intercreditor Agreement. This Note is subject to the terms and
        conditions of an Intercreditor Agreement, dated as of November 29, 2001
        (the "Intercreditor Agreement"), among Borrower, the Investors and
        certain other holders of Secured Promissory Notes issued by Borrower. In
        the event of any conflict between the provisions of Section 1 of the
        Intercreditor Agreement and any provision of this Note, the provision of
        such Section 1 shall govern and control."

                               ARTICLE II: GENERAL

        1. Governing Law; Venue. This Amendment shall be governed by the laws of
the State of California, without giving effect to conflicts of law principles.
Borrower and Lender agree that all actions or proceedings arising in connection
with this Amendment shall be tried and litigated only in the state and federal
courts located in the City and County of Santa Clara, State of California or, at
Lender's option, any court in which Lender determines it is necessary or
appropriate to initiate legal or equitable proceedings in order to exercise,
preserve, protect or defend any of its rights and remedies under this Amendment
or otherwise or to exercise, preserve, protect or defend its Lien, and the
priority thereof, against the Collateral, and which has subject matter
jurisdiction over the matter in controversy.


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        2. Entire Agreement; Counterparts. This Amendment and the Note together
embody the entire understanding and agreement between Borrower and the Investors
and supersede all prior agreements and understandings relating to the subject
matter hereof. This Amendment may be executed in any number of counterparts,
each of which shall be enforceable against the parties actually executing such
counterparts, and all of which together shall constitute one instrument.

        3. Security Interest. Borrower acknowledges that it has granted to the
Investors a security interest in the Collateral to secure the payment of all of
the Secured Obligations including, without limitation, principal, accrued
interest, other advances made under the Note and any attorneys' fees to which
the Investors are entitled under the Note. Borrower acknowledges that it has
taken prior to the date hereof all actions required and reasonably necessary to
perfect and to otherwise give notice of the security interest granted hereunder
including, but not limited to, the execution and filing of financing statements
and the filing of notices of security interests with the United States Patent
and Trademark Office.

        4. Restrictions on Transfer and Compliance with Securities Act; Investor
Representations and Warranties.

            (a) Certificates representing any of the shares of Common Stock
acquired pursuant to the provisions of this Note shall have endorsed thereon the
following legends, as appropriate.

                (i)Such shares of Common Stock will not be registered under the
Securities Act of 1933, as amended (the "Securities Act"), nor qualified (if
necessary) under applicable state securities laws and consequently will have the
following legend:

        "THE SECURITIES EVIDENCED BY THIS CERTIFICATE HAVE NOT BEEN REGISTERED
        UNDER THE SECURITIES ACT OF 1933, AS AMENDED, AND MAY NOT BE SOLD,
        TRANSFERRED, ASSIGNED OR HYPOTHECATED UNLESS THERE IS AN EFFECTIVE
        REGISTRATION STATEMENT UNDER SUCH ACT COVERING SUCH SECURITIES, THE SALE
        IS MADE IN ACCORDANCE WITH RULE 144 UNDER THE ACT, OR THE COMPANY
        RECEIVES AN OPINION OF COUNSEL FOR THE HOLDER OF THESE SECURITIES
        REASONABLY SATISFACTORY TO THE COMPANY, STATING THAT SUCH SALE,
        TRANSFER, ASSIGNMENT OR HYPOTHECATION IS EXEMPT FROM THE REGISTRATION
        AND PROSPECTUS DELIVERY REQUIREMENTS OF SUCH ACT."

                (ii) Any legend required to be placed thereon by any applicable
state securities laws.

            (b) Each Investor, by acceptance hereof or by making any Advances,
agrees that the Note, as amended by this Amendment, and the shares of Common
Stock to be issued upon conversion pursuant to the terms of the Note, as amended
by this Amendment, are being acquired solely for his own account and not as a
nominee for any other party and not with a view toward the

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resale or distribution thereof and that he will not offer, sell or otherwise
dispose of the Note, as amended by this Amendment, or any shares of Common Stock
to be issued upon conversion pursuant to the terms hereof except under
circumstances which will not result in a violation of the Securities Act or of
applicable state securities laws.

            (c) Each Investor, by acceptance hereof, represents that such
Investor is (i) an accredited investor within the meaning of Rule 501 under the
Securities Act and has such knowledge and experience in financial and business
matters that he is capable of evaluating the merits and risks of the purchase of
the Note, as amended by this Amendment, and can bear the economic risk of his
investment; (ii) aware of the Borrower's business affairs and financial
condition; and (iii) aware that the Note, as amended by this Amendment, has not
been registered under the Securities Act in reliance upon a specific exemption
therefrom.

            (d) Subject to the preceding, the Note, as amended by this
Amendment, may be transferred only upon surrender of the original Note as
amended by this Amendment, for registration of transfer, duly endorsed, or
accompanied by a duly executed written instrument of transfer in form
satisfactory to Borrower. Thereupon, a new note for like principal amount and
interest will be issued to, and registered in the name of, the transferee.
Interest and principal are payable only to the Investors or their transferees
set forth on Exhibit A to the Note.

                [remainder of the page intentionally left blank]



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        IN WITNESS WHEREOF, the Borrower and each of the Investors has caused
this Amendment to be duly executed on the date first written above.

                                  EUPHONIX, INC.

                                  By:  /s/ Jeffrey Chew
                                       -----------------------------------------
                                  Name:   Jeffrey Chew
                                  Title:     Chief Executive Officer

                                  INVESTORS

                                  /s/ Dieter Meier
                                  ----------------------------------------------
                                  Dieter Meier

                                  /s/ Walter Bosch
                                  ----------------------------------------------
                                  Walter Bosch

                                  /s/  Robert Kuhling
                                  ----------------------------------------------
                                  By:  Robert Kuhling
                                  Title: OEA Management, L.P.
                                         The General Partner of
                                         ONSET Enterprise Associates, L.P.

                                  /s/ Milton Chang
                                  ----------------------------------------------
                                  Milton Chang

                                  /s/ Stephen D. Jackson
                                  ----------------------------------------------
                                  Stephen D. Jackson


                                  /s/ Robert Kuhling
                                  ----------------------------------------------
                                  By:  Robert Kuhling
                                  Title: OEA Management, L.P.
                                         The General Partner of
                                         ONSET Enterprise Associates III, L.P.


[SIGNATURE PAGE TO AMENDMENT TO SECURED PROMISSORY NOTE DATED FEBRUARY 22, 2000]