Nicely made pedals with good sounds. Since there is no protection diode it is easy to blow the Q10 regulator FET part type FDC634P by incorrect power connection.
King of the pedals boss feature a protection diode in case of accidental polarity reversal.
I do like Hiwatt amps. Even the later pcb models sound unique.
Some of the early DT models hum intrusively. This can be reduced by lead dress improvements and altering the positions of the interstage and output transformer. The improvement is significant with 500 percent reduction in hummmmmmm.
If you would like me to modify your harp gear amp just let me know. Sending the amp in is a good option if you are not in the Bristol area.