Hey there! I've done this a while back now (last year in fact), but I thought it'd be appreciated here. I've had this lovely burgundy Honeytone amp for the longest time, but eventually the circuit in it failed. A while afterwards, I got some subminiature tubes I started playing with, and the thought of putting those inside the Honeytone sparked the begining of this project. Here's all pictures and info from the process of making it: https://drive.google.com/folderview?id=1v7-ppCu_mGSNfZdqfjUrZtzhPhdUXQ48 It was even featured in Hack-A-Day! https://hackaday.com/2018/02/19/tiny-guitar-amp-rebuilt-with-tiny-tubes/ Since then, I've swapped the high-voltage DC-DC converter board for a less noisy and smaller board, and I'm working on putting another subminiature amp inside a Benson AM4 (a cheap clone of the Marshall MS4).