Recording bass on to Mp3

Hi,

My cousin has emailed me a couple of songs on Mp3 he has done on acoustic guitar/vocals. He has asked me to put a bass line to them. I have very little knowledge of how to do this. I have Audacity downloaded on the my laptop and have used this previously to change pitch on songs I have had to learn. I have a TC electronics RH750 amp which has a digital out socket. What cable will I need to record on to Audacity, I have downloaded the Mp3 track to Audacity. My laptop is a HP Pavillion running Windows 10. Will I need to plug in to a USB socket or Mic/Headphone socket on laptop. Any other advice would be appreciated, cheers.

Only some laptop computers will have the ability to accept the SPDIF digital output from the amp as an input.
[e.g. My laptop has SPDIF digital-output socket, but it not does not have the capability to accept SPDIF digital-input ].

The more common arrangement is the analog line-out signal from the amp, to a line-in socket on the computer,
(see TIP).

If your computer does not have a line-in socket there are devices (~$35) which effectively convert a computer USB socket into a line-in socket, e.g.

NB: don’t plug line-out from the amp into a microphone socket on the computer :
the line-in signal is way too strong and the sound will be very distorted.

Thanks for your reply

Some computers can convert their mic-in socket into a line-in socket, under software control. (My Dell laptop can do that)

If your HP computer can do that, you can connect the line-out of your amp to the dual-purpose mic/line-in socket on the computer without buying any additional electronics. But only try that if your computer-manual explicitly says that the mic-socket can also be used as a line-in.

https://www.google.com/search?q=“HP+Pavilion”+“line+in”