There are a few firms who specialise in Quad who I’ve read will modify - that is reduce - the input sensitivity to suit sources like CD and streamers, which typically yield up to 2 volts. Back in Quad tuner and reel-to-reel tape days, something like 300mV was more typical. As you can imagine, 6 or 7 times the input can overload the preamp leading to distortion, and the volume control only working over the first few degrees of rotation. Neither of those are what you want!
I can’t name any places, but Mr Google should probably know.
Otherwise, attenuating the output is the way to go, unless you find a streamer that has output level adjustments - like my old Linn Sneaky DS, used only for c £400, for example.