Nice purchase Banmac, The No.20's have 50kohm input impedance and 26db of gain which will lend itself very well to a passive pre of 10kohm.
Looking at some of your other posts it seems you may have a ML No51 cd player, which has it's own very good built in volume control. If so I would go direct from the No51 straight to the No20's. You may never look at an active preamp the same way again.
From ML about the No51's volume control.
The Nº51 volume control uses a hybrid analog/digital
attenuation scheme to achieve a remarkable 80dB control range at
0.1dB resolution from 20 to 80 dB and 1dB resolution from 0 to 20dB.
By applying DSP-based digital attenuation only to fill in the gaps for
the very lowest level volume control steps, the Nº51 does not suffer the loss of resolution (EG: Bit Stripping) associated with pure digital volume controls.
Cheers George
Looking at some of your other posts it seems you may have a ML No51 cd player, which has it's own very good built in volume control. If so I would go direct from the No51 straight to the No20's. You may never look at an active preamp the same way again.
From ML about the No51's volume control.
The Nº51 volume control uses a hybrid analog/digital
attenuation scheme to achieve a remarkable 80dB control range at
0.1dB resolution from 20 to 80 dB and 1dB resolution from 0 to 20dB.
By applying DSP-based digital attenuation only to fill in the gaps for
the very lowest level volume control steps, the Nº51 does not suffer the loss of resolution (EG: Bit Stripping) associated with pure digital volume controls.
Cheers George