I posted some time ago a note
about my Velleman K4040 amplifier. The sound of the amp as built from the kit
was unremarkable and definitely not in line with the price. Lacking experience with tubes, I was looking for some time for well documented mods to the kit.
I found two 2006 posts here
and implemented them rather directly. The only difference is that I used IXCP10M45S
instead of a pair of J508 current sources in each channel and replaced the 1N5408 rectifiers with UF5408 instead of adding noise suppressing capacitors in parallel to them.
The mods did not leave much of the original Velleman design in place; the result, however, is a remarkable improvement in sound!
However, two problems remain: (1) I got hum that wasn't present before the mods; and (2) a two-year old running around doesn't get along with eight hot, attractively glowing tubes. The project is shelved until a better time.