Tailored Voltage Waveforms (TVWs) and the Electrical Asymmetry Effect they induce in plasmas are useful tools to both optimize plasma processes and gain insight into the role of specific plasma parameters (ion bombardment energy, species flux) in processing outcomes. However, the multi-frequency nature of these waveforms, which are composed of a fundamental frequency in the MHz range and a number of its harmonics (eg 13.56MHz 27.12MHz 40.68MHz….), leads to a practical technical challenge, namely multi-harmonic impedance matching. Although impedance matching the 50 ohm output of an amplifier to a plasma processing chamber with a large reactive component is easily achieved for a single frequency using a passive component matchbox, doing the same at multiple harmonics is much more challenging due to the frequency response of every circuit element (including the chamber). One strategy that has been employed and deployed as a commercial product is the use of multiple amplifiers, matchboxes, and filter sets, one for each frequency used. Although technically effective, using individual amplifiers for each frequency may not be the most cost-effective solution. Alternatively, we have previously proposed a technique to simultaneously match at multiple frequencies using a passive multi-frequency matchbox (MFMB), but this solution is difficult to optimise due to variations in components affecting the response at pairs of frequencies. In this work, we present results from a new design of MFMB using only passive components. Critically, this new design allows (1) independent control of the frequency response at each harmonic, and (2) the use of a single high-power amplifier. Circuit simulation results as well as experimental resultsare shown for a small area, laboratory plasma processing chamber during an argon plasma for three-frequency operation, and for fundamental frequencies between 9 and 15 MHz. It is demonstrated that although adjusting the matching condition for the fundamental frequency (1f) changes the matching for the other two (2f, 3f), the converse is not true; adjusting the matching on the higher harmonics does not impact that of the fundamental. Furthermore, we show that this improved matching is indeed due to better power transfer and not parasitic losses in the matching network.