Obviously, I had listened to the amp before I bought it (attached to some more exotic components) and it sounded considerably more impressive. It’s been a while since my last one died, so comparisons are pretty subjective, especially since I have also moved house.

Placing the amp on these hollow wooden boxes makes a massive difference.

After trying some other ideas (speaker wire, interconnects etc), I thought perhaps shouldn’t just have the thing laying on the floor. I had some empty file boxes to hand, so I placed the amp on top of them. The difference was massive. Apparently, the amplifier is microphonic – it can convert vibrations into electrical signals. When these new signals mix with the musical signal I would assume they inject a slightly phase shifted version of the original waveform, which in my case was quite audible.