@noromance Thanks for posting about this! I built a Waynes 2018 preamp, a DIY design from the good folks at Pass labs that I put an Alps 27K in and it is good. But you and the other contributors here have given great leads on what promises to be a significant upgrade. Thanks too to @mulveling. I don't think I can swing the RK50 but the Alps RK40 looks doable! Great stuff.
I replaced the volume pot on my tube preamplifier.
Replaced the two mono Alps pots in phono preamp with Tocos (Tokyo Cosmos), RV24 units. I heard good things about these pots on other forums. Fair bit of work getting them to fit into the Croft 25R. I had to loosen the tube boards and drill out the mounting holes for the larger threads. The pots were only $26 for both inc tax and shipping. Huge improvement in speed, clarity, solidity, and transparency. I'm blown away.