Hi,
I have a Rotel RC 1080 preamp going into a Quad 606 preamp

Here is the Rotel RC-1090









Quad 606 power amp



Quad 606 Power Amplifier Specification
Power Output: 140 watts per channel (8 ohms)
Distortion: < 0.01%
Input Sensitivity: 500mV
Input Impedence: 20Kohm
Crosstalk: -100db (100hz), -85db (1 khz) and -65db (10khz)
Hum and Noise: 105db
Voltage Rating : 220-200V AC (110-120V via simple power board modification)
Dimensions (WxHxD): 321 x 140 x238 (mm)
Weight: 12kg

The preamp out is 1v and the power amp input is 500mv

What level attenuator would I need to buy to match the preamp to the power amp
-10db or -20db or some other figure?

Thanks

Lee