I recently purchased a new SC20H. The production sticker date is 2019-34. When depressing the On/Off button for the loop there is a substantial  drop in volume. Also, there is a hum present when the loop is in use. Additionally, when engaging pedals in the loop a popping sound is present. This is not something I have experienced  with other amps and I did not expect in what is marketed as a high end Made in England Marshall. This amplifier was produced  some time ago as evidenced by the date sticker. Have these issues since been addressed? I do not want to submit a brand new amplifier for repair. I am still under the retailers return/exchange period. Would exchanging for a more recent  production SC20H resolve this issue?

Hello

Recently purchased this amp head only to find out that the effects loop does not works as advertised

I have tried an number of buffered and unbuffered pedals and the result is very frustrating

 When the loop switch is engaged with the amp in 5 watt mode there is an audible pop a noticeable hum comes from the amp/speakers and any effects connected pop loudly when engage/disengaged.

 When the loop switch is engaged with the amp in 20 watt mode (full power) there is an  audible pop a louder more annoying  hum coming from the amp/speakers and any effects connected pop loudly when engage/disengaged.

 I have also used just a quality effects pedal cable between the send/receive only to see if it’s just the pedals and the circuit still click and hums when engaged.

 This is totally unacceptable in any way shape of form and I would expect that with a brand such as Marshall and its long history of quality equipment that these type of issues would not exist as pre user testing would have sort them out!

This appears not to be the case as a number of online amp forums have pointed out that this is a know issue with this amp and no know solution or repair fix has been forthcoming from Marshall.

 Please issue a fix for this to be carried out by authorised service techs at your expense as this type of marketing and selling of equipment that is faulty and "not fit for purpose" is illegal under Australian consumer law and is most likley the case in other countries

I look forward to receiving a thoughtful and considered response to resolving this issue!