What is the best type of preamp for a class D amp?

I haven't seem all that many, but it has appeared to me that many seem to have a rather low numerical impedance; which might make a difficult match for many tube pres.

Just like any amp, a pre-amp with low output impedance relative to amp input impedance is best to minimize distortion and for best dynamics. Input impedance of Class D amps run a range similar to others anywhere from 10K ohm to 200Kohm.

For a tube pre-amp 45-60kohm input amp impedance is the minimum. For lower output impedance ss amps, most any amp will likely match well in this regard.

Avoid clipping a all costs and keep noise and distortion to a minimum and audio life in general should be good.

Class D is a modern technique for reducing power requirements of the power amp and supply for the power amp. It isn't used for preamps because preamps don't need those features. Preamps are class A.

01-30-15: Georgelofi
Many far more technical than me say none yet can be called true hiend, as technology is not yet developed to allow the switching frequency of Class D to be high enough which then has to be filtered out at the end, and that filter not to have an audible/measureable effect on the upper mids/highs of the audio spectrum.
And they also need to be able to drive low impedance loads at high frequencies, which they have trouble with at the moment.

But they do make great bass amps.

Cheers George

So Soulution, Rowland ... are NOT true hiend? Then what is TRUE hiend?