Electronics: LJM L20SE Amplifier

This power amp was originally based around two 'LJM MX50X2' modules purchased off Ebay from a Chinese vendor.
Having spent a fair amount of time unsuccessfully trying to source suitable heatsinks, I eventually went in search of a donor amplifier, and knowing that most Rotel models have generously rated heatsinks, I found an RB-956AX on Ebay for a good price, so I bought it.
It's powered by two toroidal transformers from a Cambridge A5.
I have also changed the protection circuit to a Velleman K4700 protection board (this is now known as a WSAH4700 which appears to be a fully built module - mine was a kit).
I bought two faulty Cambridge A5 amps as scrap off Ebay.
After using this amp for a few years, it occurred to me that it never sounded quite right, specifically at very low volume.
I found a thread on DIY Audio with some suggested mods to improve the amp (it was extremely under biased at 1.8mA!!) for a start.
There were quite a few mods ads follows: (reference to the original schematic - original schematic and revised schematic at the bottom of this page).

Remove Q1, Q2, 2x2.2k resistors (replace with links), add a 270R resistor between the bases of the output transistors, change values around the bias spreader and add a 1k pot.
Remove the 33k resistor and two diodes (replace the diodes with links).

The amp is DC coupled by default - I added a small board with a decoupling cap on the input. I also added a 2.2uH inductor on the output.

I tested the amp thoroughly, leaving it playing a 1kHz tone into a dummy load at various power levels and the bias (now set to ~36mA) is stable. The heatsinks run very cool (cold even) at idle.

Overall, I feel this was quite an improvement, the hardness has gone from the sound (especially at low volume) and the amp generally sounds cleaner and more detailed.