I’ve fitted a new pickup in the bass. The previous pickup was a passive piezo and these suffer with impedance problems driving cables and amplifiers. It worked – it just didn’t sound very nice.
I did look at putting a DIY preamp into the bass, but overall it was much simpler to put an all-in-one solution in. This was the Fishman Presys Blend:

- It was fairly cheap on EBay;
- It was a brand name so I’ve got some chance of getting another one for another instrument;
- The amp frontplate is flat – most are curved to fit into guitars or ukuleles. Obviously this bass is fairly (very) flat.