There's no such thing as impedance matching in the context of hi fi. The matching of SUT's to cartridges is about as close as we get... It is a concept used mainly in RF circuitry. Even the term impedance is usually not strictly correct unless one wishes to be really pedantic as resistance is usually more apt a term. As Andrew says, all you really need is for the driving impedance to be much higher than the input impedance.
For the op I would check if the DAC has a selectable output level and can be turned down. Unlikely in the case of the Arcam but many pro DACs can have a higher output level selected.
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