For a tube pre-amp, the Xiangsheng 728A is a good introduction, about $300 and presumably not difficult to resell . My experience is at
https://audiokarma.org/forums/index.php?threads/buyers-report-xiangsheng-728a-tube-pre-amplifier.963...
https://audiokarma.org/forums/index.php?threads/buyers-report-xiangsheng-728a-tube-pre-amplifier.963...