Suggestions for Preamp Tubes

Friends,

I seek your suggestions for preamp tubes.  My preamp is a Quicksilver remote control line stage preamp that came equipped with two 6DJ8 tubes.  Mike Sanders, who built the preamp, confirmed that I can substitute  the stock tubes with 6N1P, 6AQ8, 6922, or 7308 tubes.  The treble seems a bit bright, although the bass and mids seem lovely to me with the 6DJ8 tubes.  Should I try another option from among these alternatives?

The other components in my system are:

Audiolab CD transport

Cambridge Audio CXN100 Streamer

Cambridge Audio DACMagic 200M

The aforementioned Quicksilver preamp

A custom tube amp with four Tung Sol KT150's

and Klipsch Cornwall IV's.

Any suggestions on whether to swap the preamp tubes and, if so, with recommended options will be greatly appreciated.

Thanks,

Jay